James moans and tries to pull out from under you. Instead, you roll on your back and let him sprawl over your belly and chest, still stuck on your huge shaft. He shakes his head, blinking. "Oh, man. I feel really weird. But really good."
You know what he means - your cock seems to be even bigger inside him than it was, and your testicles throb with heat and growing pressure. Then you gasp and thrust in spasms as another gush of semen spurts deep inside James' body. He gasps with you, clutching his arms around his chest and arching back with his eyes wide and mouth open. You cum yet again, and this time his head snaps back as a gush of thick white fluid shoots from his mouth.
James looks as startled as you, and then struggles wildly to pull his arms free. You can see that they are no longer separate - they are melting into his chest. Looking down, you also see that his legs are rapidly dwindling even as your balls expand. Staring harder, you realize that James is becoming part of your body - your sexual equipment, to be exact.
He looks scared now. "Make it stop! I can't feel my legs or arms, and..." Another ejactulation makes both of you shudder, and he spews more cum. You grab him to steady him, but feel your hands on his skin as if you were touching your own cock. Amazed, you rub his chest and sides, and are rewarded with intese sexual pleasure.
James is getting smaller now, his panicked eyes staring helplessly. The jets of cum are steady, preventing him from speaking, each gush leaving less of James in mass, and a shape more like a throbbing penis. His head is sinking back into his shoulders, and his whole body looks rounder.
You know he is terrified, that each time you feel pleasure he is becoming more and more a part of your body. But the sensations are too incredible, and as you rub him, his skin suddenly loosens and slides down from his shoulders! Slick pink flesh is underneath what has become a thick foreskin.
James' struggles get slower as his body stiffens more, still shrinking, and now quite obviously a monster penis. His face is flattening and flared, nose gone and mouth closed into a piss slit. He cums again and again as you masturbate madly, overwhelmed by lust.
All that is really left are his eyes now. The look of terror fades as his brain is absorbed into cock flesh, becoming dull and expressionless before even they fade into the swollen dark head of your powerful cock. You cum at least three more times before you are finally spent and collapse back on the bed in exhaustion.
It takes a while for your thoughts to clear, and when you finally look down at your crotch again, you see a huge, dark, but normal-looking cock and balls. James is now just your sexual organs - and what must be ten gallons of cum splattered all over you and the room.