hahaha.. it's true, it does stem from racist slang.. I actually didn't realize that until years after I first heard the term from some West Indian friends (and more recently on the Chappelle show). It's become so ingrained into my vocab that I can't help but use it.

"Comedian Dave Chappelle, on his program Chappelle's Show, featured a joke advertisement for a sleep aid specifically for black consumers known as "ribs," consisting of pork ribs cooked in barbecue sauce, explaining that it induces a state known as "the itis.""