Rob suddenly found his transformation, a fact he could feel as his muscles pulsed throughout his body, rather invigorating. His penis grew erect with all the sensations and vitality flowing through him.
And almost immediately, it began to shrink.
He saw everything through his trousers. Through his trousers, he saw his penis shrinking; growing more into the proportions of a boy at the cusp of puberty, rather than a young man completely through it.
And almost immediately, it shrunk to the prepubescent nub of all young boys.
And then, with one big slurp, it shrunk right into his body.
Rob stared at his trousers, jaw hanging.
His penis was now gone, leaving only a small slit in its place.
Rob knew one thing; the tf site had worked after all. He was turning into a monster.