Your're Gonna Get Your Ass Kicked

Michael Rapaport has a message for Conor McGregor -- Floyd Mayweather's gonna kick your ass all the way back to Ireland!!!

Rap was sitting front and center at Floyd's training session at his Vegas boxing gym on Thursday night -- where he says it became crystal clear McGregor has not shot on Saturday.

He also blasted Conor for being an obnoxious, style-jacking, culture misappropriating poser.

Rapaport also says he saw Demi Lovato at the training session -- and was upset because she didn't look super pumped to be there.

"Why are you here Demi Lovato?! I don't know why you're t the gym. You should be excited that you're at the gym, 'cause that's greatness you're watching, 49-0."