When you have sex in the dark with a girl that thinks you're a different person but you aren't aware she mistook you until after the deed is done.
"How'd you lose your virginity?"
"Oh, I pulled a Casper The Friendly Ghost, once I realized she mistook me for someone else I got the hell out of there!"
Ruler of Lake Titicaca. Rumored to have a bunghole that gets very angry if it does not receive toilet paper. Cornholio the Great is often seen walking around with his shirt over his head and his hands in the air, chanting songs about his power, and his bunghole.
"I am Cornholio! You do not want to face the wrath of my bunghole, for I need TP!"
Butthead: Shut up, Beavis! (uh huh huh huh)
Beavis: Um, okay. (heh heh heh heh).