If “gay rapper” is an oxymoron where you come from, how to get your head around the notion of a gay rapper performing in a sports bar? What in most cities might seem plausible only as some sort of Sacha Baron Cohen-style provocation is just another weeknight in the cultural Galapagos that is New Orleans. Sometime after midnight on the sweltering Thursday before Memorial Day, the giant plasma-screen TVs at the Sports Vue bar (which “proudly airs