Together with ''South Park,'' its Wednesday-night lead-in, Chappelle's Show has gone a long way toward helping Comedy Central finally live up to its name. A prankster with a mile-wide grin, Dave Chappelle knows no bounds when it comes to machine-gunned ridicule -- in addition to easy satirical targets like Hollywood and Madison Avenue, the profane stand-up's skits just as exuberantly lampoon white and black racism (with a healthy, hilarious dose of the N-word). It's his determined playfulness that makes his embrace of ethnic and racial stereotypes not offensive but refreshing. He baaad...but oh so good. EXTRAS Five of the 12 episodes feature for-fanatics-only commentary by Chappelle and cocreator Neal Brennan, and a half hour of bloopers and deleted scenes feels superfluous given the no-expletives-barred treatment throughout. This set is randy enough without them.