To complain.
To add weight or strength to; to beef up.
To fart; break wind.
Ugh, who just beefed in here?
To feud or hold a grudge against.
Those two are beefing right now - best you stay out of it for now.
To cry
David was beefing last night after Ruth told him off
To fail or mess up.
I beefed my presentation hard yesterday.