r u mad?

A mocking question to someone you know is angry, usually used in the context of griefing in online games.

A questioning joke that one person nerviously asks another. The nervousness stems from the fact that the person asking the question is not sure whether the person to whom the question was addressed is really mad or not.

Usually responded to with:
Yes=Trouble
No=Time to utter a funny banter

O Y R U MAD @ ME? is an expression that means oh why are you mad at me?.