Chris Brown has a message for Rihanna ... and any other guy who might want a piece of her ... back off, because "THAT IS MY P**SY!"Chris was partying at Emerson Theatre in Hollywood early Thursday AM when he grabbed the mic from the DJ and went off on how to talk to your woman -- and the bizarre rant was all caught on tape.Chris said, "You GOTTA say that one thing to her ... Don't make me have to tell you again, that's my p***y baby! ... so you better...
