With that, Terry stripped down to his y-fronts.
David and Danny watched in awe and amazement as their dad gained pale purple splotches all over his body, which then began to spread all over, save for the hands and feet.
POP!
A small thin tail with a triangle end Popped out from his behind, above his underpants.
His legs shrunk a bit, and his bellybutton was replaced by a huge yellow slitted eye.
Terry's fingers became elongated claws, with clawed nails.
Then, Terry's hair turned blue, his hands and feet turned green, and pink spots patterned his back.
Within seconds, Terry was no longer human, he was a monster!
Terry admired his monster self in the mirror. "I look ferocious." He said to himself. He growls in satisfaction.
When he dipped his hand down his y-fronts, he found his penis had gone, and in its place was a slit.
"Well I'll be damned!" He said. "I've lost my dick!"
(Terry had failed to take into account that when the transformation site turned males into monsters, their penises would be removed, or transformed into vaginas.)
Terry pulled his sons into a hug, and they fell down laughing.