"I just saw this documentary about these kids with Tourette's syndrome," Matt LeBlanc exclaims on the upcoming Showtime series Episodes. "You've got to see it. It's . . . so . . . funny."

On the show, an inside-Hollywood comedy about adapting a British TV franchise for American audiences, LeBlanc stars as . . . Matt LeBlanc. Sort of. Much of Episodes' humor comes from seeing the actor who played Joey Tribbiani, the dim-witted sweetheart on Friends, do mean-spirited things like laugh at children with neurological disorders. And LeBlanc's not the only star breaking bad. Recent comedy is littered with examples of actors cheerfully besmirching their good names.

The trend was popularized by films like Being John Malkovich and series like The Larry Sanders Show and Curb Your Enthusiasm—whose creator and star, Larry David, pioneered the actor-as-himself-as-asshole approach. "Even though you assume Larry is an exaggerated character, there's a part of you that thinks, 'I bet you that's who he is,' " says Episodes cocreator Jeffrey Klarik. The same dynamic was at play in the Harold & Kumar movies, in which Neil Patrick Harris, then still better known as Doogie Howser, played "Neil Patrick Harris," a libidinous, Ecstasy-popping car thief. Similarly, Daniel Radcliffe will always be Harry Potter, but Extras fans also know him as a sex-obsessed, condom-snapping creep. Carl Weathers may have been an eighties action hero, but on Arrested Development he turned out to be a cheapskate given to plundering the craft-service table. And Entourage has transformed the most wholesome TV personalities—like Full House dads Bob Saget and John Stamos—into egomaniacal freaks.

It isn't hard to figure out where the credit (or blame) for all this meta-comedy lies. "Reality television has made audiences and producers more aware that authenticity is a performance," says James Bennett, author of the new book Television Personalities: Stardom and the Small Screen. "As we witnessed more over-the-top personas on Big Brother or America's Next Top Model, we were also let in on the joke that 'being yourself' is a performance." So just as everyone on Jersey Shore turns into an irredeemable jackass when the cameras start rolling, LeBlanc turns into one on Episodes when the fictional cameras stop rolling This play on "being yourself" is why we chuckle when Patrick Stewart declares on Extras that he's written a screenplay about using telekinesis to make women's clothes fall off. Or when Josh Groban tells a tipsy sixtysomething on Glee, "Josh Groban likes a blowsy alcoholic." Dozens of actors are willing to play obnoxious, narcissistic, or criminally insane versions of themselves these days. They see it as a savvy career move, one that shows they can poke fun at Hollywood stereotypes. "It's less douchey to go on TV and send yourself up than to act way too serious and into yourself," Groban says. "I like to give the audience the benefit of the doubt that they know fiction from nonfiction."

Not that they always do. After the singer voted for a rival group while serving as a celebrity judge in one episode of Glee, he recalls, "There were a lot of tweets that said, 'Man, Josh Groban is an asshole!'"

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