She fucking did it

James recognized the grey top he was wearing. And when he pulled down the neck and his tits spilled out he recognized those, too.
"Crazy bitch," he muttered in his ex-girlfriend's voice. "She fucking did it."
His nipples were already hard from staring at himself, and he caressed one of his breasts lightly as he pondered his situation.
James's ex-girlfriend had become obsessed with swapping bodies. She wanted to experience life as a man and she wanted him to understand what it was like as a woman. Her obsession was why James broke up with her. She was hot as hell but it came with a lot of baggage.
He hadn't seen her in four months until he found himself in her body. One second he was in the grocery store and the next he was in her apartment, the baggy grey tee shirt his only article of clothing. There was her body beneath him and he felt  himself up with his new hands. He was still physically attracted to her, and his attraction was manifesting itself in his damp thighs and the spike of heat between his legs. 
Despite the confusion, despite the fear, he was horny as hell. Had she done this? Warmed her body up for him? 
Whatever it was he had to follow that feeling, and he tore off his clothes and stroked himself, growing wetter as he listened to his own cries, until he enjoyed one of his ex's incredible, moaning orgasms. She was every bit as sensitive as he remembered.

A young man clones his mind into the bodies of four women at an anime convention and uses them for his own ends in Cosplayed, available on Smashwords and Amazon. Preview here.