Now that I've thought about it for a little while, I feel kind of bad about mocking Jim Carrey over his STD history.
He may have just had a bad sexual experience with a zombie who he mistook for a horny groupie.
It would, of course, have gone for his biggest brain - the one he keeps in his pants... ;-)
He might also have been bummed when he realized after he "finished" that he couldn't transmit an STD to the zombie.