Possibly the nastiest Christmas movie ever made, director Terry Zwigoff's follow-up to his critically acclaimed Ghost World is also an unbelievably funny work filled with sex, cynicism and liberal usage of the 'f' word. Miracle on 34th Street this ain't.

The story follows department store Santa Claus Willie T. Stokes (Billy Bob Thornton) and his dwarf buddy Marcus (Tony Cox), who every year pose as a Santa/elf combo, and then proceed to rob whatever outlet they're working for. Stokes is a former felon and foul-mouthed drunk with a total lack of respect for anyone and anything. Marcus, who has a normal-sized girlfriend, is a bit more temperate, but can still fling scatological insults with the best of them.

Working at a Phoenix department store, the duo become involved with The Kid (Brett Kelly), an eight-year-old dweeb tortured by all his classmates, who believes the profane Stokes really is Santa. Taking advantage of this, and realizing The Kid lives only with his senile grandmother (Cloris Leachman), Stokes moves into his house, which he uses for trysts with hottie barkeep Sue (Lauren Graham), who has a sexual thing for guys in Santa outfits.

It's difficult to describe how truly down-and-dirty Bad Santa is, but Stokes' opening monologue, which filthily details his downward descent as a human being, certainly prepares the viewer for what's to come. Among the highlights: Sue having sex with Stokes in the backseat of a car while screaming, "Fuck me, Santa!" Bernie Mac as a department store detective, stirring powdered "stool softener" into his orange juice while in conference with store manager John Ritter (in his last screen role). Stokes' f-word-filled responses to kiddie toy requests. And a boxing match between Marcus and The Kid featuring plenty of below-the-belt blows.

There's more. Much, much more. Zwigoff seems to be having a wonderfully perverse time with this material, directing it with a speed and economy that make the film go by in a breeze. And Thornton, who looks appropriately dissipated, gives a terrific performance as a rascally curmudgeon for the ages. In particular, his shouted insult matches with Cox (also hilarious) are in the so-funny-they-hurt category.

Funny as it is, Bad Santa is problematic box-office material. It's certainly not for kids, and will definitely turn off more conservative adults. The raunch content seems perfect for male teenagers, and if nothing else, this ode to nastiness will probably have a long life as a cult item. Bad Santa could do for department store Christmas displays what Animal House did for fraternities.

-Lewis Beale