"Ha, I wish I was a girl!" Andrew laughed. Steve almost gave himself away, knowing full well that Andrew was in for the surprise of a lifetime.
Andrew waited, and at first he continued to laugh the stuff off. Until he chest started feeling... different. He looked down and saw his nips were clearly outlined in his shirt. They were too big, too round. Too... feminine.
"Shit!" Andrew doubled over as his chest expanded. His flat pecs gained shape and grew. Two new round orbs of flesh formed, bouncing freely inside Andrew's strained shirt. His torso thinned, losing muscle tone and definition. The next change hit Andrew's hips. They cracked and grew ever so slightly. He put his hands on them, running over his new curves. Then traced the outline of his new tits.
"Oh, wow that's good." Andrew moaned as his hands ran over his erect nipples. His hands softened, as did his face. Hard lines became smooth, and he lost all facial hair. His short brown hair grew until it was about shoulder length. As Andrew continued to moan and sigh, his lips became fuller, and his nose shrank. His fingers circled his big nipples, and eventually he tore his shirt from his body to really play with himself. Cupping his boobs, Andrew guessed he was bigger than his own girlfriend. And they were still growing, unbeknownst to him filling with milk.
Andrew was so absorbed in pleasuring himself, he didn't even notice the changes to his lower body. His feet shrank at least three sizes, becoming petite and hairless. The rest of his body dwindled to next to nothing. Smooth skin left in its wake. His thighs gained mass, adding to his curvy appearance. The most notable change came to his crotch. Andrew was expecting to feel himself getting hard. But as his penis and testicles retreated into his body there was a new sensation assaulting him.
He felt wet. Like he was pissing himself. Only he knew it wasn't piss. He kicked his jeans off, and then tugged his boxers down. There, where his cock and balls had been, was a soaking wet slit of flesh. An inch long nub appeared at the top of the slit, and when Andrew touched it he just about blacked out.
His, more like her, clit was incredibly sensitive. It was like a compact version of her former cock. Andrew's hips bucked forward, and wetness spewed from deep inside him. His first female orgasm sent him over the edge, and he collapsed on the floor.
Meanwhile, Steve was still hidden in the bathroom, playing with himself too. Seeing his friend grow breasts, and watching his cock and balls being sucked into his body only to be replaced by a pussy was too erotic NOT to do something.
Steve's horsecock flopped out of his pants, and he quickly started pumping up and down. His orgasm came shortly after Andrew's. Horse seed landed on the floor, covering Steve's own feet. He took deep breaths to calm himself, and then exited the bathroom.
Andrew was passed out on the floor, completely naked in his new female body. Her pussy was still very much swollen and wet. Steve could SMELL how needy Andrew was. He turned his head and spotted the container of Transformation Salve.