"Holy cow, it actually worked!" Cecil's girlfriend exclaimed from right next to him. He awoke with a start, surprised by the sudden shout, and tensing up underneath the covers of his bed.
His head was throbbing, and he couldn't recall the night before. Had he even invited his girlfriend over last night? Cecil did remember meeting up with Emily at the party yesterday. She had even paid for some of his drinks, and she'd stuck close by him the entire evening.
Turning around, he saw Emily seated at his bedside, back turned towards him, her frame ever so slim, her hips...
Huh.
"Babe," Cecil asked, "what happened?" The question referred to his lapse of memory of last night, as well as the reason for Emily's sudden bout of excitement.
She craned her neck to look back at him, wearing a smug grin on her face.
"I'll show you what happened, babe. We fucked last night, and I came out the winner!"
"The winner?"
"Heck yeah!"
She stood up from the edge of the bed, and turned around. Cecil recoiled as his eyes were suddenly assaulted by the sight of Emily helicoptering a penis, her penis, in front of his face.
"Emily, what the hell?!" Since when did she have one of those?
His girlfriend giggled like a maniac, before catching her breath to explain it to him, though with a story that did not at all sound familiar to him, or realistic in the slightest at that.
"I told you that I wanted to try out being the guy in our relationship one day, remember? You promised the last time we visited, but you were too big of a pussy to try it out in the end."
"What drugs are you on right now?" Cecil asked.
"You don't want to believe me, huh? How about you look down for me again?" She asked rhetorically, pointing down towards the cock that was somehow attached to her pelvis. Her hips had narrowed as well, becoming more masculine. And a scrotum hung just below her new member too.
"But how?" Cecil wondered aloud.
Exasperated, Emily threw up her arms. "Basic biology hun! Try not to feel too embarassed by your predicament. I'll keep it only for so long, I promise. I win some, you lose some. Next time you get to be on top again. If you still don't believe me, I suggest you stare at my cock a little bit longer."
Cecil did what Emily told him. He was confused, but somehow not entirely fazed by his girlfriend's new addition. Remarkably, the longer he stared, the more his excitement grew. Emily too, was growing a boner because of the sudden onset voyeur, and its growth sparked something from within Cecil that he had never felt before.
Warmth, from deep within his belly.
Wetness too.
Feeling his arousal, Cecil pressed his arms against his spine, revelling in the feeling he received from stretching into the pleasure. At the same time though, he discovered something amiss with his own body.
Not long after, having thrown the covers off of himself, Cecil discovered truly for the first time just how the universe's rules of biology and evolution had changed for him, in an instant, while he was drunk asleep next to his girlfriend.