1. Sarcastic racism. Using racism to be ironic.
2. A way to get away with being really racist by passing it off as being tongue in cheek.
See: Sarah Silverman, Wonder Showzen.
Spelling variations: Racasm, raccasm, and sarcism are all acceptable variations, but racecasm is widely accepted as the most common spelling because it leaves the least confusion as to what the term is implying as well as how it should be pronounced.
1. JOKER: My black friend's birthday is coming up.
POLITICALLY CORRECT INDIVIDUAL (PCI): Oh? How nice.
JOKER: Yes. I'm not sure what to get him, but I've narrowed it down to a bucket of fried chicken, a carton of menthols, a watermelon, a year's supply of Kool-Aid, a copy of Big Ass Monthly, some chronic, or the same brand of watch that he already stole from me.
PCI (noticeably uncomfortable): Um...
JOKER: Relax, bro! I'm not serious. I'm just using racecasm!
PCI: What does this have to do with a marathon held annually in the Grand Canyon?
2. SUBSTANDARD COMEDIAN: Look, there's a nigger!
WOMAN IN AUDIENCE: Oh, my God!
SUBSTANDARD COMEDIAN (later that evening making a televised apology): I was trying to go for shock humor. I'm afraid it was a misguided attempt at racecasm.