You have to imagine what it felt like when the director yelled, "Cut!" and everyone collapsed on the set and said, "Can we get away with this? Is nothing sacred?"
Billy Bob Thornton's performance is—there's no other word—beautiful. When Thornton played the James Carville figure in Primary Colors, his timing was great but he didn't have that outsized, demented, swallow-the-world quality that Carville himself radiates; Thornton is curdled and bilious, with sallow skin and liver lips. He doesn't click in every part but he's the greatest Bad Santa imaginable. He's in a tradition of Southern/Texan misanthropic derelict nihilists, the arena of Hunter S. Thompson, Harry Crews, and Terry Southern. Those of us who love it (and not everyone does, to say the least) go for the mixture of the archly sophisticated and the potty-mouthed.
Bad Santa is a gonzo parody of a Christmas redemption movie, but it also hits all the Christmas redemption movie beats, which means you also get that warm fuzzy feeling while Lauren Graham is chanting, "Fuck me, Santa. Fuck me, Santa. Fuck me, Santa" while Thornton goes at her from behind. It isn't really subversive because it doesn't have subversive ideas: It's domesticated gonzo, like the equally fun but much cleaner School of Rock. Willie's Christmas epiphany is when he stands up for the kid, who's being bullied by some skater boys. Later he tells Marcus, "I beat the shit out of some kids today ... but it was for a purpose."
The kid, meanwhile, is dopey and ingenuous—or, to use the patois of Billy Bob's Willie, a retard. It isn't entirely clear if he believes that this criminal alcoholic pervert is Santa or that he thinks this is the best Santa someone like him could ever get and therefore chooses to believe. I think it's the latter, which brings a tear to my aged eye. Yes, Virginia, there is a Santa Claus. It just depends how low you're willing to sink.