Without thinking his hand thrust deeper into his underwear. His hand fit as the usual tightness caused by the vanished package was gone. His hand already knew its way around vaginas, even before pleasing Julia he had many girlfriend - and none of them could complain. His fingers felt around and he discovered just how changed it all was. His slit continued all the way to his man butt and he thrust his middle and ring fingers inside. It was hot, moist and so sensitive, his whole body twitched. Few classmates gave him a quick look as he caused a noise, but Mark was unaware.
His fingers continued on their way inside. It was unbelievably tight, but as swollen and lubricated it was, he could still move inside him a bit. His breathing started to quicken and deepen a bit. His thumb made its slow and awkward (due to the angle) way to his new clit, now begging for attention. He started to circle his clit slowly with his the surface of the thumb. It almost sent him flying.
This was wrong on so many levels, he thought. I've got a different stuff in my crotch, I don't know how it happened and now I can't stop touching it in class. What if someone saw? I'd look like a major pervert! Mark thought, but his hand would not come out of his pants. His fingers quickly thrusting back and forth, his thumb expertly dancing around the clit. He whimpered, afraid, but also from the pleasure. He was playing around as he always did, but the added experience from feeling it all was everything. It was so different from just stroking. Not worse - just different. His whole hand was moving to find the position better.
He was masturbating his new pussy scared but so excited. His breathing heavy and getting louder he felt the waves starting to rise in his body. His fingers got even faster. He climaxed and his body jolted, his head started getting heavy along with his eyelids.
He gasped audibly and everybody looked at him.