The person being called this is basically being called a nob or a penis, basically a cooler word for dickhead/nobhead. The word originates by 3 lads from the Tarn (centre of the world to others who are from there... u know who you are) when they were in Liverpool
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).