Admittedly, the primary emotion running through your mind right now was pure confusion. As you scroll through the vast list of animals displayed on the screen, you can't help but wonder what this machine was even meant to accomplish. Yeah, of course the people who would use this machine knows what an anus is, this is a sex shop. So then... what was with the detailed descriptions? What was it with all of these animals? And... what was with all of these 'options' that were displayed everywhere? You hope to god that this machine isn't going to display some sort of animal pornography when you click on one of these options... though then again you highly doubt this store would even still be open if they actually had something like that here. Still, you can't help but feel a little nervous, like you're being watched from behind, and yet... the store is as relatively empty as it was when you came in. The person behind the register even seems to have stepped into the backroom just a moment ago while you weren't looking. However, with your mind so focused on the problem at hand, you don't seem to think that it's odd at all that such a huge store would be so barren, and you turn your attention back to the screen. If you're gonna see what this thing's deal is, you'd best do it now.
Flipping through the large variety of animals before you, you eventually decide to just randomly pick one, not really having any sort of preference. You tap the hippo button and are immediately greeted with the 'lovely' image of, what else, a picture of a hippo's backside. You scoff in disgust. Figures. Yet to the side, you also notice that the information section has rewritten itself to mainly talk about hippos, though it's mostly things like diet and... yeah. Scrolling down are the same options as before, along with a bright yellow textbox reading that it is strongly recommended that the user adjust the machine's settings first before confirming their 'choice', whatever that meant. Not really thinking, you randomly screw around with the options to see what happens.
Shockingly, things slightly DO happen. You find a 'gender' tab and press the 'female' option, and the photo of the male hippo seems to swap to a female one. Perhaps these are meant to be... erm... 'preferences'. If something screwy does happen here, you should probably get your phone out to record it for the police or something... but then again, you find yourself second-guessing yourself. Once more, you set the 'duration' for random and turn off all 'senses', worried on what exactly that might entail given just what you're getting into here. At last, you scroll to the bottom of the page, where a large neon-blue 'start' button awaits. Hesitantly, you press it, before another small screen shows up to confirm your choices. You shove aside the feelings of dread you find yourself enveloped in and press confirm, expecting something horrible, only for... nothing to happen.
Well, nothing as far as you're aware, anyways. Almost as soon as you hit the button, the screen turns black, and you're left sitting there, confused and naked.
...Naked?
Wait... since when were you-?!
You blink, and suddenly become aware that you're not in the same room as you were just a second ago. You're sitting on a cold, concrete floor in a sparsely decorated room. The only things of note you can even see are a couple of flickering lights illuminating the room, a window, and... mirrors. Wall-length mirrors that cover three of the walls, leaving the window wall untouched. You shake your head in confusion, then in fear. You notice a large roll-up door next to the window, the same kind of door you'd expect to see in a garage, and without thinking you scramble up to rush over and open it. At least, that was your intention... but your body doesn't seem to feel like running today. Almost instantly after standing up, you feel a wave of dizziness and nausea wash over you, and you fall forwards on your hands and knees in the middle of the room. You pant heavily, your stomach gurgling loudly as if you had just eaten the biggest meal of your life... hell, you certainly FEEL that way. Have you been poisoned?
You look towards the window. Perhaps, you think, you may be able to see somebody on the outside, and they may come in to help you. It was a silly thought, you knew that, but even then you didn't expect to see what it was that you saw outside the window. It was dark outside, the space only being lightly illuminated by about two or three street lamps high above the enclosure. The hippo enclosure, to be exact. You could see several, sleeping in the small water pit or just off the shore, with colorful murals painting the wall that made it very evident to you somehow that this was some kind of zoo exhibit. But then... what was this room? Some sort of staff room? Were you kidnapped and put in here because of that machine? You find it too hard to think more in depth about these things, the onslaught waves of sluggishness that have enveloped your body and the noise of your belly are making it hard to hear your own thoughts. Groggily, you find yourself slipping down completely onto the ground, belly lying flat on the concrete.
... Well, maybe not 'flat'. Your belly is actually pushing against the floor quite hard. You don't recall ever being that chubby, and yet in a matter of minutes you seem to have developed quite the potbelly. Was this the result of the poison as well? You moan in discomfort as your stomach continues to loudly growl. It's far more noticeable now. Puff. Puff. Gurgle. Grow. It feels like your stomach is pulsing, with each successive wave causing your belly to grow bigger. And bigger. And bigger. Eventually the pulsing stops, though the bulging certainly doesn't, instead being replaced by an overwhelmingly strange sensation of discomfort coming from within your body. The feeling is nearly indescribable, as if you should be in sheer agony right now, and yet you feel nothing but a slight internal moving sensation as your belly wobbles and bulges out more. It's as if your organs were either shifting around or growing new pieces within you... or perhaps both. You pant heavily, sweat practically pouring out from your forehead like a waterfall. Why the hell was it so hard to think right now, and... why the hell were you so aroused by this?!
Slowly, you try your absolute hardest to turn your head towards the mirror to your side, your body feeling somehow even more unresponsive and sluggish than before. If your eyes had the energy to widen more, they would be bulging out of their sockets at the sight before you. Not only does your entire torso look like it's about to pop open at any millisecond, but your skin is... different. It's significantly darker than before, almost like it's heavily bruised, but you don't think that's the case. Not only is it not even remotely painful somehow, but in the light of the flickering headlamps your new skin seems to glisten. To the best of your current ability, you brush your hand against your elongating chest, feeling a wave of additional pleasure from just how smooth it's gotten, and evidently how the rest of your body is going to become, judging from how the purplish-brown coloration seems to be spreading, seeping through your skin and rapidly overtaking your formerly pale complexion.
You groan as you make another effort to push yourself up off the ground, but your arms just aren't responding anymore. Your legs, on the other hand, seem to sprout a mind of their own. You feel a strange twinge flow through your body, almost like a small static shock, as your legs seem to slowly rise on their own. You pant, staring in the mirror, as your legs push up onto your toes, your bare ass exposed to the elements, being covered in the same smooth, dark skin as the rest of your body. Your odd position certainly doesn't help with your discomfort, your back beginning to join in with your chest and belly as your entire midsection gurgles and pushes outwards. However, you note, your ass is... different. Looking in the mirror, your butt doesn't seem to be growing at all... as a matter of fact, your buttcheeks seem to be shrinking. You feel a tightness in your entire private region, like somebody is pushing your butt up towards the rest of your body, as you watch your ass shrink. It almost looks like two balloons deflating, however no air is coming out. You wonder what's happening to your internal organs and bones, as surely your innards would need to go somewhere if your body was shifting this much. For a moment you consider that perhaps it's all being pushed into your stomach, but that doesn't seem right, after all if your leg bones were being sucked away then your butt wouldn't be stuck in the air, after all. Once more, a wave of dizziness overtakes you as your thoughts become distant and hard to formulate. In fact, now it almost seems harder to think about anything in general, as your head is suddenly overtaken by an immense pressure like your butt. Not on the outside, but on the inside. You clench your teeth and desperately attempt to move, as if to stave off these feelings, only for the feeling to disappear as abruptly as it came, and with it... there actually was movement.
... Your anus feels like it's moving. In the mirror, you look absolutely grotesque, your ass is almost entirely flat with just a hole sitting there exposed to the elements. 'Almost' entirely flat, because there is a slight bump on your rear, but it's not your asscheeks. It's your anus itself, as the skin around it seems to be puffing outwards and pulling your hole farther out from your body, looking almost like a round volcano. However, somehow, that isn't the weirdest thing about your butt right now. The real weird thing, is that your anus appears to be moving on it's own. It's not just pulling and puffing out like the rest of your body, but it's opening and closing and... wiggling around, as if something was living under your skin and was trying it's hardest to burst through... but there was a hole right there. There was nothing inside of you doing this, your anus is... a- alive? The machine flashes in your mind for a brief moment before your legs start following your butt's lead. They twitch and writhe on their own, but not quite like if you were having a muscle spasm, more like you were just trying to move them and stand up like before... but you weren't. In fact, you can't seem to move them on your own at all anymore, and you don't believe that's because of how bulbous you've become. The pulling becomes more intense on your anus, as the rest of your butt finally seems to start bulging out slightly along with the rest of your body, along with your legs. Though you can't feel them, you can certainly feel them swell up, swelling with fat and slowly being consumed by the same dark coloration as your belly.
You can't take it anymore, you're so terrified yet so horny at the same time. Part of you screams to reach for your penis to relieve yourself, but you know that isn't possible anymore. Almost on cue, though, you are suddenly overtaken by extreme pleasure, almost as if you were jacking yourself off right there... but there was nothing there, nothing that could be tugging on your penis other than... well, your rapidly deforming body. If you had to describe it, your entire body felt like it was being pushed from your head to your rear, with your ass rapidly twitching and swelling and your penis feeling crushed up against your crotch by an invisible force. Your poor dick is being crushed under the increasing mass of your legs, your feet having strangely lowered down slightly. You're no longer standing on your toes, in fact you can't feel your toes at all. Your feet have become enveloped in the same strange pushing sensation, like your toes are being crushed back into your body, becoming rounder and softer with each pulse. Likewise, your penis also appears to be getting smaller, with your balls no longer dangling beneath them like normal but instead being securely attached to your backside, becoming just another part of your skin. However, before they can be completely absorbed, your entire body suddenly floods with perhaps the biggest pleasurable feeling you've ever experienced in your entire life as shockwaves of orgasmic joy fill your whole being. You're cumming so much, it almost doesn't even feel like your cumming at all, more like you've sprung a leak. Your cock and balls start to shrink even faster now, before the last drop of cum falls onto the ground behind you and you feel the last remnant of your stick, your urethra, seal up with a small squeezing sensation.
You release a loud, guttural moan from the feelings still wracking your body, never seeming to dissipate even despite your dick disappearing. However, *you* didn't make the sound, you find that making any noise at all is tremendously difficult, even crying out or screaming, as rather the sound had emitted from behind you. If you could still scream, you would be screaming even louder than you were before from the sight in the mirror. Your anus is... well, it's not an anus anymore. You seem to be sprouting a second head from your butt, as your rear starts to expand and swell in strange ways. Your anus is stretching out horizontally, moving up and down, with a moving sensation from within your bowels suggesting the formation of teeth and a waggling tongue. The skin immediately over your hole is expanding outwards even more from before, bulging outwards into a snout-like formation. You feel a strange pinching on the top of your head as two new ears form down there, as well as perhaps the strangest sensation of all so far. You can feel two small sections of your butt-snout giving way to move pressure, but on the opposite side. Two new holes carve their way through your body and into your rectum, giving way to a sudden massive rush of air entering you from behind. Your ass is fucking breathing.
Two more bumps form above the snout, suddenly opening up and blinking curiously at the strange circumstances it was in. Eyes. You can't believe what you're seeing right now, and you're absolutely horrified with the realization of what's happening. The head you're seeing right now looks just like that of a hippos, you were fiddling around with that machine, and you randomly picked 'hippo' from that list- and- You want to cry as you feel your arms and hands swell outwards, your fingers slowly disappearing into the rounded mass of flesh and becoming part of the back of a circle. The back. You picked 'anus' off the list, and you were turning into a hippo.
... Well, not *a* hippo, as you've probably gathered.
As the hippo continues to gain more and more control over your body, slowly starting to stand up on its own, you can feel another great pressure on your former chest, now the hippo's lower abdomen. Surprisingly, your nipples have remained as they were before even despite the swelling of your stomach. However, they seem to be growing even more than the rest of your body. The orgasmic feelings that are still wracking your body are only amplified by the swelling, your breasts gurgling and bulging more and more, ballooning outwards between your new hind legs. Breasts, no, teats, you realize. You had left the hippo's gender selection on 'female' when you were experimenting with the machine. You'd mentally slap yourself for this if the situation as a whole wasn't as fucked up as it was. You can feel a new pressure building on your upper chest, just below your neck, which is in and of itself beginning to get absorbed into the hippo's backside. You feel it swelling more, the back of your head being pulled back and pressing up against the hippo's rump, though not before you feel a suddenly even larger rush of pleasure as the region just below your neck puffs outwards and opens up. A vagina, for the new she-hippo that has replaced almost your entire being.
As of now, you're just a human head disturbingly attached to a hippo's butt. You want to turn away from the mirror, you don't want to look at something like that anymore, but your neck is so swollen that turning your head is nigh impossible. However, even despite your protesting, the hippo herself is moving around on its own. It's completely taken over control of everything, your being has become completely numb, as your ever diminishing brain is no longer linked to your senses. It's becoming harder to hear, taste, and smell as you metaphorically speak. The hippo seems to have taken a moment to get a grip on its surroundings and ability to move, before it's suddenly overcome by a weird urge of its own. Slowly, the hippo maneuvers itself over towards the biggest mirror in the room, before turning around and presenting itself to it. You're left staring at yourself in shock and fear, barely able to think of anything anymore other than the fact that the situation is horribly wrong. Part of you wishes, nay, all of you is praying that the transformation will end there. As freakish as you look, you know what the machine was implying, you remember the in-depth descriptions and pictures that it displayed. You hope that it's all just you being too anxious and that this bizarre nightmare will be over soon enough... but deep down you knew that it would all be too good to be true.
Your neck continues swelling, pulsing and rounding out the hippo's rear further. It was taunting you by showing you the changes, you assumed. Slowly, the purple skin finally started to creep onto your face, as your scalp started to feel itchy and tight. Your hair starts to fall off in clumps, starting with the very back of your head. As the back of your neck grows and fuses with the hippo, your hair is torn aside and flops off as your head continues to raise higher and higher, eventually completing with a small 'pop' as the last of your back-neck skin is pushed onto the end of the hippo's back, rendering all hope of movement you had left completely gone. The back of your head is now completely fused to the animal, with your lower neck starting to overtake your chin. Before it can, though, the rest of your hair falls off over your face, nearly blinding you as some remnants get caught on your nose and eyes. The hippo itself sways it's back from side to side, shaking off the remaining hair. You can feel a pulling sensation on your forehead, as a small hippo tail begins to form. The tail seems to be drawing mass from your nose, as you note that you can no longer see it in your peripheral vision, with your nostrils sealing up with another tight squeeze and leaving you as just a pair of eyes and lips at the end of a round, round butt. You know what's coming next, you know what the next change is going to be.
Almost right on schedule, the orgasmic feelings from before seem to have migrated solely towards your head. The hippo lets out another loud noise of pleasure, at least you assume, as you helplessly watch the final changes take place. There's another gurgling sound, more distant than before yet somehow so close, as your sense of hearing slowly dissipates along with your ears. The smooth hippo skin starts to dye your cheeks, as you can feel them begin to puff up, like they were filling up with air very slowly. Your cheeks slowly start to jiggle as the hippo slightly sways more and more, enjoying what's happening for herself. Your cheeks start to compress what little is left of your face, starting to grow so large as to overtake the already huge, albeit bare, behind the hippo was sporting before. They wiggle and sway, puffing and puffing bigger. Your vision is beginning to be taken over by darkness, though you don't think that's just because of your new asscheeks slowly concealing you behind their ever-expanding size, but also because your eyes are beginning to become hazy. Your remaining senses starting to dissipate along with your brain. You find it difficult to even comprehend what is happening to you anymore at this point, words becoming difficult to formulate or even remember as your head begins to shrink beneath the cheeks. They jiggle and pulse and grow and puff, and you can feel your- no, your host's tail begin to lower over them, blocking out all remaining light.
Finally, your lips begin to feel chapped, yet smoother than ever before, as the hippo skin starts to invade your mouth. You feel your tongue, stuck to the bottom of your mouth. Slowly sinking into the mass, becoming just another part of the hippo's bowels. Likewise, your teeth begin to feel softer, lighter, slowly shrinking back into your gums, which in and of themselves are receding, slowly reducing the inside of your mouth into the opening the machine decided it was meant to be. Your lips begin to wrinkle, and slowly compresses itself into a circular shape. The sides of your lips feel like they're moving closer and closer to the center, partly due to the force of the asscheeks growing ever larger still and from the same pressure that you're felt all throughout the change, making your mouth smaller and smaller. However, it's not just your mouth. You wanted to be an anus, after all, not just a part of you. As such, the pressure begins to increase. Your eyes, the space where your former nose was, and even what little bit of your cheeks wasn't puffed out into the hippo's bottom all begin to shrink even more. It kind of feels like a tickling sensation at this point, your entire face shrinking and scrunching up together. Your mouth, in a way, feels like it's turning inside out somewhat. Your lips are being sucked into the hippo's body, attaching itself to the hippo's bowels and morphing to form the entire anus, pulling down the rest of your face as well. You aren't sure when exactly you lost your eyesight given how dark it was already by that point, but by the time your flattened sockets begin to pull inwards your eyeballs have almost certainly flattened and morphed into more hippo flesh, the sensations of your entire face conjoining together to form the sensation of just being one giant mouth, which you are in a sense.
There's no more thinking coming from you, you're only barely aware of anything at this point, a small part of your brain having conjoined with the new brain of the hippo in order to leave you semi-conscious, though otherwise completely mindless. You're an anus now, a hole, perhaps the most disgusting part of any animal's body, and yet all of your prior concerns and reservations about this had been swept away along with your consciousness. The hippo, suddenly freed from its trance, snaps back to reality and trots over to the garage-like door to it's pen, which seemingly opens on its own. You feel a sudden pleasurable cold wetness as your blubbery hole-y self is submerged in the zoo pen's makeshift lake, as the newly formed she-hippo settles in for a long night's rest. Soon the pleasurable feelings fade, as you hadn't set any specifications for your senses in the machine earlier, none of them were left. Perhaps, in the little bit of consciousness you have left however, you should probably pray that the random duration you accidentally set this for wouldn't be long... or, perhaps don't worry about it. Your lack of thought may be a good thing for now, after all if you were conscious you would probably consider your new up-'n-coming experience to be rather shitty.