The changes came quickly.
My cum was making girls grow cocks. And the idea of it obsessed my friends. I invited Hannah over, everyone skipped class and called in sick from work, and we entered into a week long, cum filled orgy. Ali and I were milked for every drop that we had. She claimed that she was staying at our house to observe the changes in the other girls, for science. But all her waking hours were filled up with pumping as much spunk into our friends as she could manage without passing out. So she didn't have much time to take notes. All the girls wanted what we had.
It didn't take long. Dani joined us on the second day of the orgy. We were in the living room. I was taking Amanda from behind, my cock sawing in and out of her dripping snatch. Dani was on the couch in front of us, legs spread to give Amanda's questing tongue access to her slit. Hannah was on the floor next to us, barely conscious, a growing pool of cum leaking out of her stretched asshole. I was approaching climax, about to fill Amanda, when Dani's moans peaked and then turned into a shocked scream.
"Oh my god! Guys, I think something's happening!" She pushed away from us, sliding back on the couch. Amanda and I watched, stunned, as Dani's pussy spread open and the fat head of a cock pushed it's way out. It was an interesting sight. Ali and I had just woken up one morning with dicks attached to us, so none of us had seen this first moment before. Dani's back arched, her head tilted back, mouth open in a silent scream. It kept coming, inches of throbbing flesh flowing from her pussy, looking incredibly massive on her slight frame. When it was over the fat head of her new cock was resting between her breasts, precum already flowing from her tip.
"Holy shit," Dani whispered. "This feels better than I expected." She pushed her tits together, trapping her dick in a cage of soft flesh. She began thrusting her hips, giving herself a tit fuck. Precum shot from her tip and splashed against her face. Dani moaned as she licked her lips clean. She looked down at me and Amanda. " I need to fuck someone. Now."
I reached out for her hand. "I've got a couple of free holes for you." Dani pulled herself up, cock bobbing in front of her and splattering precum down onto Amanda's back. She stepped behind me and settled onto her knees. I moaned as she pressed the wide head of her cock against my slit. With a single thrust she split me open, her cock pounding into my cervix. It felt incredible.
"Oh shit. Is this what it's always like for you?" Dani punctuated her question with another deep thrust.
She felt so good that I could barely speak, my eyes rolling back into my head as my pussy convulsed around her length. Finally, I was able to collect my thoughts. "It's always tight, and wet, and perfect. Fuck me hard!" My moan turned into a scream as her cock got even thicker. Dani must have learned a new trick. "Did you just do that?"
"Yeah. I just have to concentrate..." Dani's voice trailed off. She was still for a second, and then her cock expanded again. It felt like she had a log buried in my cunt. I could swear I felt my hips spreading open to accommodate her girth. I came, girlcum spraying out of my pussy to pool on the floor.
And then Dani really started to fuck me.
We turned into a machine. Dani thrusting deep into my cunt, pushing me down into Amanda's abused slit. Amanda pushed back, sending me straight onto Dani's pussy wrecker of a cock. Hannah had managed to sit up against the couch, eyes like saucers as she watched us fuck. Her fingers were plunging desperately into her pussy. A moan escaped my lips as she added her thumb and pushed her hand in to the wrist, fisting herself.
Dani was a natural. Her hands were wrapped around my breasts, roughly pinching and tugging at my nipples. She was pulling her cock almost all the way out of me on every stroke. The return trip filled me to my absolute limit, hitting every spot in my pussy along the way. I was in a state of almost perpetual orgasm, my pussy dripping and flexing around her. A near constant stream of cum was flowing into Amanda's pussy, squeezing out around my cock and getting churned into a froth by the energy of my fucking. I had a moment a clarity, a sudden realization of how absurd and insane this whole situation was.
But an instant later Dani came, destroying any rational thought in my mind. Her cum was like a fire blooming inside of me. I arched my back and wailed, a massive load of my own spunk spraying into Amanda. Dani's cock flexed in me as rope after rope sprayed against my cervix. I could feel my final wall dilating, hot cum flowing directly into my womb. I lost strength in my muscles and flopped down over Amanda's back, content to lay there as Dani filled me to my limit and beyond. It took its toll on her too, and she fell back, her cock coming free of my pussy with a wet pop, her last few shots of cum landing on my back in burning hot lines.
Eventually, I found the willpower to push myself off of Amanda. Cum poured out of her gaping pussy. Dani was on the floor behind me, gasping for breath. Her cock was ridiculous, knee length and as thick as her thigh. I said a silent thank you to the medical trial that gave me the ability to stretch around something that huge.
Dani propped herself up on her elbows and looked at her massive prick. "Whoa," she said, reaching out to rest a hand on the throbbing flesh. "I may have gone a little overboard." Her eyes closed, after a second she began to shrink. In the space of a few breaths her cock was half of what it had been. Still wonderfully big, but manageable. She looked up at me and smiled. "Let's go show everybody else."
They were suitably impressed. And not far behind with their own transformations.
I was buried in Kelly's ass when I felt a sudden pressure. She went stiff and silent, until a low, shuddering moan escaped her lips. I looked over her shoulder and saw the wide mushroom head of her shaft staring back at me. Without saying a thing she bent her neck and swallowed herself, feasting on her cum while I filled her ass with my own thick load.