Dave Chappelle has spent a good chunk of his professional career being the best part of some dire movies, and with good reason. As the gifted comedian says in the audio commentary for the first season of Chappelle's Show, he's improvised entire film performances, which helps explain why he's such a crackling live wire in Con Air, Woo, and 200 Cigarettes. Chappelle improvises throughout his eponymous TV sketch show, as well, but he certainly can't claim the series' scripts drove him to it, since he and partner Neal Brennan wrote or rewrote pretty much every sketch featured on the uncensored initial Chappelle's Show collection. The show typically takes a sturdy premise, often rooted in racial and gender stereotypes, and then fills it out with inspired improvisation from Chappelle, whose quick mind and nimble comic riffing have a way of animating even the weakest bits. Sometimes, what he says is less funny than how he says it. In a racially fueled parody of Trading Spaces, for example, his gruff patriarch barks "Who the fuck is Renée Zellweger?" as if the very existence of such a person is an insult to his being. The series opener throws down the controversy gauntlet with the show's most talked-about piece, a skit in which Chappelle plays a blustery, black, blind white supremacist. Re-conceiving one of the most incendiary ideas from Sam Fuller's pulp masterpiece Shock Corridor as basic-cable comedy, the sketch is more audacious than hilarious, but lines like "America's at war with al-Qaeda, but we're still losing the war against Al Sharpton!" can't be written off as mere provocation. As befits a series built around a self-professed lover of poop jokes, Chappelle's Show habitually goes too far. Chappelle and Brennan don't seem to think a joke can be too obviousas evidenced by bits like a urine-themed R. Kelly parodybut usually, sound comic judgment backs up the show's bad taste: It's too crude and uneven to be hailed without reservations, but too funny and vital to be dismissed. Comedy Central has been billing its reruns of Mad TV as the edgiest sketch-comedy show on television, but this first-season DVD of Chappelle's Show illustrates that Mad TV isn't even the edgiest sketch comedy on Comedy Central. Not by a long shot.