The ability to masturbate skillfully with both hands. When one hand is tired, the other hand may be used to continue just as effectively. It is also possible to create unique combinations using both hands.
Guy 1 - I was trying to fap last night, but my right hand got tired, so I had to stop.
Guy 2 - I don't have that problem; I'm fapidextrous. I can go as long as I want.
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).