Getting an MRI is unpleasant. It's cold. And shockingly loud. You'd expect a sterile white tube to emit, at most, a gentle hum. The whines and thumps that the hidden machinery let out were not improving my mood.
It didn't help that I was completely naked, lying perfectly still, listening to commands from Ali through a speaker.
I'd agreed to let her study me and the changes that had happened to my body. After all, it was her medical trial that had resulted in me growing a huge cock. And all the things that followed from that. The least I could do was help her figure out what had happened.
Of course, I got to fuck her when we were done. So I could handle a little discomfort.
"How are you doing in there?" Ali's voice sounded distant as it came through the speaker.
"Can we just get this over with? I don't really like it here."
"Ok." I could hear the amusement in her voice. "Go ahead and do your thing."
"How big do you want me?"
"Um. Let's start normal and then go up from there."
Normal for me was still pretty big. My cock pushed out of my pussy, spreading my lower lips. I let out a happy sigh as it flopped up onto my belly, a foot of hot throbbing meat. Muscles somewhere inside of me flexed and a small dribble of precum leaked from my tip.
"Ok, just hold there," Ali said. The machines around me whirred and knocked. "Emma, I'm getting some good data here. What I need you to do now is start to get bigger, but try to do it slowly. That'll help me see what's going on."
I did what Ali asked, inches of dick flesh creeping out of me. The spongy head pushed between my breasts, leaving a slick trail of pre as my length increased. Finally I was maxed out, my tip just brushing my chin. My head flared, and a large burst of precum dribbled out, soaking my neck. Once my cock was unleashed it started to get a mind of it's own. I'd need to cum before it would go back down.
The MRI continued to work around me for a while. My cock twitched and flexed the whole time. A steady stream of pre trickled out of me, pooling in the hollow of my throat. A particularly violent spasm passed through my length, shooting out three ropes of sticky sweetness onto my face.
Eventually, the machine surrounding me went silent. I heard a door open, and the sound of Ali's heels on the tile floor. The padded bed I was lying on began to slide out of the MRI.
Ali grinned when she saw the state I was in. "Making a little mess in there, are we?" She reached out and dragged a finger through the precum that was running down my cheeks, bringing it to her mouth for a taste. Her other hand gently stroked up my length. My hips thrust up involuntarily, searching for something to fuck. I tilted my head up just in time to capture my crown between my lips as a mouth-filling shot of precum burst out of me. Ali let me suckle on my tip for a minute or two before she wrapped her hands in my hair and pulled me off of myself. I came away with a whine.
"No cumming yet," she scolded. "I need you to do that while the machine can record it."
I was confused. "Aren't there a couple of problems with that? I'm gonna cum all over that thing, and I don't want to clean it up. And, you said I had to stay very still, so it can get good pictures. How am I going to get myself off if I can't move? I'm not a wizard."
She just smiled. "I thought of that." Ali reached into the pockets of her lab coat and pulled out a condom and a small egg shaped vibrator. "These should take care of things."
"Ali, you may not have noticed, but I cum a lot. I don't know if a condom can handle me." Don't get me wrong, I like the way I taste. But a hospital was not the place to have a condom full of cum explode all over me.
"You might be surprised," she said, unwrapping to condom and unrolling it over my head. It looked like pink cellophane, extending just past the ridge of my crown. "Condoms can actually hold quite a bit of fluid."
She fished a roll of medical tape out of her pocket and taped the vibrator to me, pressing it against my flared ridge. She looked down at me. "You ready?"
I nodded and laid back down on the bed. Ali flipped the switch on the vibrator before sending me back into the depths of the machine.
The vibrator was very effective. It didn't take long before I was gasping and struggling to stay still. Precum started to fill the tip of the condom at an alarming rate. I watched in amazement as the thin latex stretched and swelled. The ball of pre was the size of an apple, and getting bigger, as it began to droop down towards my chest. My breath was coming fast now, my heartbeat pounding in my ears as I tried to hold on just a moment longer. Then I let the floodgates open. I groaned as cum poured out of me. The translucent ball of pre became opaque. The condom swelled alarmingly as I filled it with liquid desire. The heavy weight of my cum pulled the condom down until it rested on my chest, a burning hot bulb that dwarfed my breasts.
I cradled the hot balloon of cum as I slowly slid out of the machine. It was amazing what my body could do. I only hoped that Ali would be able to learn something from all these tests.
She only smiled when she saw the full condom hanging off the end of my cock. "See? I told you it would hold enough." Ali reached out and carefully tied off the condom. "I'll just keep this as a sample."
I cleaned myself up and got dressed as Ali went to look at the data. By the time I joined her in the control room she was staring at the screen, her mouth gaping in astonishment.