Wiz Khalifa Challenged By UFC Fighter: I'll Make You Crap Your Pants!!

Brown and yellow?

If Wiz Khalifa wants to get the actual crap beat out of him, UFC bad ass Felice Herrig says she's more than happy to do the honors ... if Wiz wants to test his MMA skills against a real fighter.

As we previously reported, Wiz has been doing some fight training in L.A. -- so, we asked Herrig to assess the rapper's skills.

She loves him as a rapper, but Herrig says he'd need to get a big ol' diaper if they ever stepped in the cage 'cause the fight would be a repeat of what she did to her opponent back in June.

BONUS -- Herrig also takes a shot at rapping the Eazy-E classic, "Gimme That Nutt" ... and let's just say she's a better fighter than a rapper.