Just like "You mad bro?", this mocks someone one who is raging with anger. It can also be an additional mocking phrase to "You mad bro?"
Guy 1: *screams, shouts* THAT BITCH
Guy 2: ....
Guy 1: God, I f'ing hate that bitch!! ARGHH!!
Guy 2: You mad bro?
Guy 1: STFU!
Guy 2: Why you mad tho???
Guy 1: -__-
by Black Zeus December 25, 2011