1- gaining significant muscle mass
2- the act of drinking protein shakes, then hollaring "YEAH BEEF IT UP" , one may also do a series of push ups after drink has been chugged.
3- increasing anything in large amounts
Ouch, I was beefin' it up yesturday and I think I'm sick. YEAH BEEF IT UP!
1: The dogs had a great time at the park. They had a good time beefin' it out with each other.
2: Sorry bro, I know you're in the shower but is it cool if I take a squat and beef it out real quick?
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).