"you be illin" means "you act crazy" So, if your friend does many strange things you can say to him "you be illin!"

this is not a dirty expression?

I guess only fucking Niggers could say that, it's not definitely English. Question - do you hate us Niggers? Answer - You are better than the white folks in some ways, and too stupid to take the power. Obama is just a white Nigger. He represents the facade.