This is a movie about a very bad Santa, indeed. He’s worse than bad. He’s vile. He’s disgusting. Billy Bob Thornton plays Willie, a department store Santa who is constantly either drunk, horrifyingly inappropriate and obscene to the kids, or having sex, sometimes all three at the same time.

Willie and his partner Marcus (Tony Cox), an African-American little person, get jobs as Santa and elf in a different department store every December. Then they rob the store’s safe on Christmas eve and pretty much blitz out until the next year.

It’s a pretty close call as to whether Willie is more throroughly disgusted with himself or the rest of the world. But it doesn’t much matter to him. He seems incapable of holding onto a thought of any kind, much less a goal or plan. Then, in a demented twist on the usual movie plot, Willie meets a boy (Brett Kelly) who appears to really believe he is Santa and whose completely pathetic disaster of a life begins to wake Willie up to some all-but-vestigal notion of compassion.

Most of the movie is the same joke over and over — Willie’s grossly (in both senses of the word) inappropriate behavior. Willie tells a child he got into trouble for having sex with Mrs. Santa’s sister. This is supposed to be funny. Then, when the child walks in on him while he is having sex with a pretty bartender who has a Santa fetish (Lauren Graham of television’s “Gilmore Girls”), the child says matter-of-factly, “Hello, Mrs. Santa’s sister.” This is supposed to be even funnier. I am always up for something twisted and demented, especially in the midst of the overstuffed and over-marketed holiday season, but “Bad Santa” just gets sad.

The movie begins to feel more shoddy and exploitive of the child than Willie is as it tries to have it both ways, skewering and embracing the conventions of the holiday movie and the holidays themselves. Despite some funny moments, the best efforts of Thornton and Cox, and top-notch support from John Ritter as an anxious store executive and Bernie Mac as the store detective, the movie runs out of steam and becomes just unpleasant.

Parents should know that this movie has extremely mature material, including non-stop smoking, drinking, and profanity (often in front of or addressed to children), exceptionally explicit sexual references and situations, and graphic violence, including a suicide attempt, hitting below the belt, murder, and shooting.

Families who see this movie should talk about what made both Willie and Marcus decide to change.

Families who enjoy this movie will also enjoy the rude humor of Ruthless People and The Opposite of Sex. Other twisted holiday tales include Scrooged, Gremlins, and the brilliant A Christmas Story.