Ben hit “Enter” with the cursor hanging over the “Extra Extra Large Draft Horse” option. Immediately, a sharp electrical sensation hit his whole body, concentrating in his groin. He shuddered and let out a gasp as his back jerked.
It got better quickly as the feelings subsided somewhat. He opened his eyes and looked down between his legs. His pants were bulging up somewhat as he popped an erection. The electricity felt good now, as his penis began to grow, thickening and lengthening rapidly. His whole body, in fact, felt like it was getting bigger. More muscular. Powerful.
He shuddered again as a curious pressure built up in his face. He reached up and touched his nose, only to find his mouth was distending. It felt awkward, but not uncomfortable. His fingers were changing as well, he realized. The fingernails were growing thicker. Four of his fingers started fusing together, leaving just two fingers and a thumb on each hand. His clothing tightened up around him as his chest grew larger and his legs thickened.
He struggled out of his clothes, but it was too late to take them off. He let out a whicker of distress as his shirt busted at the shoulders. Shrugging, he pulled the tattered cloth off easily.
He groaned as a sudden new sensation hit him. His groin felt packed and heavy and full. His pants were positively straining with tightly packed cock and he shivered as he squeezed the big bulge lightly. His bare skin felt alive and electric as he flexed, experimenting with his new muscles. He smiled and whickered loudly, enjoying the powerful sensations running through his body.
He stood up and walked into the bathroom, pausing on the way to kick off his shoes - his feet fused into hooves somewhere along the way (complete with horseshoes, which he thought was a nice touch on the part of the programmers). He gazed at himself in the bathroom mirror, turning this way and that. His long, beautiful mane grew thick and wavy, starting between his horse-like ears and ending down towards the middle of his backside. His tail hung out over the edge of his pants in the back, and he experimented with swishing it back and forth. His rump looked hard and firm and absolutely perfectly formed.
His chest was deep and muscled, with well-defined pecs and abs. A ten-pack of abs, in fact, and his fingers explored the deep grooves, sending pleasure running through him. His cock bulged, throbbing visibly as he watched in the mirror. His pants stretched tight around the thick rod as it pushed down his leg, continuing to grow and expand, pulling the pants tighter and tighter. Enormous testicles swelled at the base, further filling his overwhelmed pants.
His breathing grew heavy and his chest rose and fell quickly as his thick, clumsy fingers stroked over the huge shaft inside his jeans. He moaned as a large wet spot appeared towards his knee and thick fluid ran down his skin. The head of his shaft bumped up against his knee, unable to move down farther, and the shaft continued to swell and grow. It was soft to the touch - flaccid, as far as he could tell - but still growing alarmingly fast. He shuddered, moaning as more thick fluid spurted from the tip. It looked like he had a nice flair developing on the head…
He gazed at his horse-self wondrously, in awe of the changes that came over his body. He looked like the epitome of the Greek ideal in horse form with a huge cock, an idea he really enjoyed thinking about.
He flexed again, tightening up his whole body, from toes to thighs to abs to arms. His pants ripped off then, unable to hold him in any longer - he was growing larger all around, and was now at least half a foot taller than before, not counting the ears. As his pants fell away in shreds, his huge horse-cock flopped out. It was a mottled pink and brown and hugely thick. The widely flared head hung down past his knees, but rapidly grew harder, thickening up considerably as it raised itself up. It was thicker than his wrist by far and at least as long as his arm.
He groaned as he watched himself in the mirror. His huge shaft was half-hard now and bent slightly in the middle, where it fell over. He gripped it about three-quarters of the way up with his right hand, moaning deeply as his cock jerked from the touch. He gripped tightly, squeezing the still semi-flaccid shaft tightly, before sliding his fingers over the head to collect some of the thick cum dripping out there. He used it to lubricate the pink and brown shaft, bringing his other hand up to stroke as well.
His hooves danced on the floor, thunking heavily, as he panted and snorted. His cock raged and throbbed as his brown skin bulged with muscles. He continued to grow, gaining another foot in height and the equivalent mass all around. His cock nearly doubled in thickness and added another foot in length, at least, maybe more. He couldn’t tell by this point, as he desperately jacked himself off, unable to think of much more than that.
His hips bucked as he let out several more snorts from his now fully-equine face. The whites of his eyes gazed into the mirror as he watched himself in rapt fascination, unable to remove his view from the hulking, masculine, god-like figure masturbating there. He shuddered and a huge spurt of cum splattered on the mirror. He was really getting off on this, the rampant narcissism, but who wouldn’t?
He smiled, thick teeth showing dully. He’d call his friend over later, but for now… now he’d take care of more immediate concerns.
He grunted and another splatter hit the window. Both hands were now firmly gripping the huge shaft as his powerful hips thrust back and forth, sliding the huge, slippery, wet shaft in and out of his fingers. His heavy, titanic balls slapped against his thighs, pounding wetly, and more cum flew from the tip. The huge crown flared large as he let out a loud whinny and came hard - his urethra bulged as a visible wave of cum traveled from the base of his cock to the tip, exploding with considerable force to completely white-wash the mirror.
He panted as cum spurted out in thick waves. The ropes were at least two inches thick each as they arced out, fell to the floor, moved farther away, and then drew back in before the next pulse hit. A gallon of cum or more flooded his bathroom sink and counter, dripping onto the floor and over his hooves and legs. He brought his huge shaft up and let several thick jets pour over his chest and belly, then his neck and shoulders, and finally he opened his mouth widely and took a couple shots that way, shuddering as cum filled his mouth and ran over his lips, dripping messily off his tongue and onto his wet chest.
It seemed like ages before his cock quit cumming. He breathed hard, supporting himself with one arm gripping the countertop, and let his cock fall heavily onto the tile, smiling pleasurably as the meaty shaft slapped down with a satisfying thwock and a splash of cum.
The horse smiled at himself in the mirror, barrel-chest heaving with exertion. His cock stayed mostly hard and his balls ached for more. He squeezed the base reassuringly as he groped for a towel with his other… he was thinking up a good plan to entice over a friend for some nice, messy fun… but first he needed to clean up the place.