You wake up. The first thing you groggily notice is a significant weight pushing down on your chest. There's something else that feels strange between your legs, but that is a distant concern. You open your eyes and look down bleary eyed. Your vision is still blurry, but you see what looks like two extremely large breasts pushing up the sheet.
You have a moment of panic; you sit up, feeling your boobs shift as you do, they sway and jiggle slightly as you stop moving. You rub your eyes and look again.
Definitely breasts. You slept in a t-shirt. It's pulled tight across them. It reminds you of your girlfriend's common complaint. No shirts fit both her chest and the rest of her. The boobs hanging on your chest look even bigger than hers.
You can't see your crotch past your bust without leaning forward a bit, but you can feel your morning wood straining against your boxers. So that's a relief.
You quickly examine how your body feels. The weight of your breasts pulling at your chest and shoulders is a very prominent sensation, as is their slight movements every time you breathe. Your arms and shoulders feel normal, as does most of the rest of you, but there's something strange going on between your legs, below your balls, and some vague sensations inside your lower body.
You turn to get up, to head to the bathroom and look in the mirror. Your breasts have inertia, as you turn you feel them lag a little, one pushing back against your chest, the other pulling. There are more strange sensations between your legs as you lift and move them to get them off the side of the bed. Then as you stop turning your breasts continue, swinging just a little to one side then swaying back and forth for a moment, pulling at your chest, just slightly making your upper body wobble too, imperceptibly to anyone looking, but you can feel it.
You stand, still more motion and pulling from your breasts as you lean forward, then straighten. As you start walking, they bounce in rhythm with your steps. You feel something else though, your hips seem to sway a little more than you're used to, changing the feel of your stride. You try to stop, but it doesn't feel like you're actually tilting them more, just that you have to compensate for something.
Your bathroom is attached to your bedroom in your apartment, so it doesn't take much walking to reach it. You look in the mirror and see yourself.
Your face and hair are unchanged, as is your upper body, aside from the breasts. They are *definitely* bigger than your girlfriends. They cover a surprising amount of your broad chest. You can see your nipples poking little tents in your shirt visibly larger than they were, like a woman's.
You scan down the reflection of your body to your hips. They're wider than they were, not a lot, but noticeably so. You don't really have a feminine curve, your waist is still the same, so your body tapers from your shoulders to your hips, then flairs out there. That explains why walking felt so strange.
That leaves the strange feeling between your legs, below your balls.
You slip your boxers down, again feeling your breasts swing forward as you bend over slightly. They continue to sway for a few seconds, pulling at your chest. The way they hang further from you pulls on your shirt, stretching the fabric and making it squeeze your ribs just a little. You can feel the fabric sliding over your nipples. It feels a little rough, but also almost pleasurable. You can tell your breast are *sensitive*.
You look back to the mirror, once the waistband of your boxers is below your hips and penis they slide all the way down, but you can't see anything unusual, just your penis and balls. You bring your hand to the front and lift your balls out of the way. You see it. It takes a moment to fully register what it is, a vulva.
You bring your other hand to it. Still leaning forward, your upper arms are pressed against the sides of your breasts. It feels very strange, like your arms are touching your pecs. Your hand reaches it. Your fingers slide along your folds. There's a little wetness there, like your new parts are just as active as your old ones in the morning. It feels good, about the same as running your hands along your balls.
Your finger reaches the top of the slit. You gasp. You've hit your clit.
You move your hands away and stand up straight again. Your breasts bounce slightly from the movement, then settle.
You just stare at your reflection for several minutes, unsure what to do, before you remember the strange dream. An alternate world. That must be it. You've been transferred to an alternate version of yourself. You're surprised at how calm you are.
You head back to your room and open your laptop. A few minutes of googling and reading later and you know at least what is anatomically different.
Babies are still born with either a penis or a vagina and go through puberty at the same age and in the same way you would consider normal. In fact, they develop in exactly the same way until around age 20.
At that age their second puberty begins. Men begin developing breasts, and their uterus and ovaries form inside them, as the area between their testicles and anus becomes a vulva and opens connecting the vaginal canal to the uterus. The development of the vulva and uterus takes around 6 months. Breast development proceeds at around the same pace as it does for women, just starting later, so some men's breasts are still growing in their late 20s. After about the first two months straight men will find they start having different feelings about the idea of a penis on women, they'll start to like it, in the same way as a straight woman. Gay men find themselves starting to notice breasts on men and shift their feelings about vulvae.
For women their penis grows, first the head forms, at first just a dark patch on her skin above her vulva, and grows both out and in, forming the internal structure as it grows out. Shortly after the penis head starts push out another patch of skin attached to it will change colour and texture, and begin forming the scrotum. After 4 to 6 months, she will have a fully functional penis. The rest of her body usually remains unchanged. After a about a month women will find their sexuality shifting, straight women starting to notice breasts on men, and feel differently about their vulvae, and gay women start to like penis.
You digest this information. You're old enough that you're finished your second puberty, aside from perhaps some breast growth, though with the way the weight of them feels, you hope they don't get any bigger. You imagine your girlfriend with an erection. You feel a surge of warmth in your vagina, female arousal!
People feel separate arousal for each of their 'halves'. Once one 'side' becomes turned on enough it will take over, shutting down the arousal of the other. If the female side does this the penis will soften and even pull inside the body, along with the testes, and the scrotum will pull itself tight to the body.
You stretch, feeling your shoulders pull up on your boobs, lifting them. You head over to your dresser and open your underwear drawer, as you expected there are bras in it. You pull one out and look at the tag, though before you even read it you find that you know what size it will say, 40I. You also have some idea of what that means. Your broad masculine chest gives the 40 band size, and the I the cups. 40 for 40 inches around your chest, just below your bust. Your girlfriend wears a 36H, but the cups get bigger not just with the letter, but with the band, so your bust is substantially larger, but then again, so is the rest of you.
You put the bra on, surprised to find it doesn't take much effort. You know how just as much as you know how to put on a shirt. You feel the weight of your breasts pulling on your shoulder substantially lessen as you get them properly settled into the cups of the bra, now the band snug around you is taking that load. You take a few steps. The extra lift from your hips still feels strange, but the bouncing and jiggling of your breasts is substantially reduced. It's more comfortable than you expected. A little tidbit of information rises in your brain telling you it came from a specialty store for larger sizes, apparently most people are wearing the wrong size, but you've got very much the right fit.