For the first time since her unforgettable appearance in the Farrelly Brothers' 1998 gross out comedy "There's Something About Mary" Cameron Diaz fulfills her comedic promise. That "Bad Teacher" is every bit as dirty though not as raunchy an R-rated comedy comes as a welcome bombshell. The filth is kept primarily on a verbal level. But there are some real zingers. A hilarious scene involving a bedroom act of frottage between Diaz and Justin Timberlake goes over the top backwards.

Diaz plays bimbo-turned-middle-school-teacher Elizabeth Halsey. After her recent divorce Elizabeth is obsessed with raising enough cash to pay for breast enlargements she imagines will attract a wealthy replacement hubby. Elizabeth is willfully less than marginal as a junior high teacher. She likes to nap at her desk while letting her students watch classroom related movies like "Stand and Deliver." Diaz commits completely to her anti-heroine character with scene chewing assurance. Breasts are exposed. Splinters fly. Pot is smoked. Justin Timberlake's Scott Delacorte is a new-hire teacher who sports a bow tie as a marker of his family's wealthy pedigree. The trouble for Elizabeth is that Scott is attracted to her rival teaching associate Amy Squirrel (wonderfully played by Lucy Punch). Ms. Squirrel is a goody-two-shoes teacher who sees right through Elizabeth's unsubtle plans. Between some guffaw inducing dialogue and inspired physical slapstick lies a romantic comedy without a lick of romance. Here's a rare Hollywood comedy that actually makes you laugh.

Inevitable comparisons can be drawn with Terry Zwigoff's 2003 movie "Bad Santa." Where Billy Bob Thornton's foul-mouthed malcontent of cynical design posed a mild threat of bad influence on the kids he encountered, Elizabeth poses a threat mainly to herself. The satire here is clearly aimed at the insidious idea that plastic surgery to a woman's boobs will alter anything other than the way she already presents herself to the opposite sex. It's interesting to extrapolate on the idea that boob surgery probably isn't so popular in the lesbian community. Elizabeth proudly tells Ms. Squirrel that she doesn't eat "muff pie."

Jake Kasdan (director of "Walk Hard: The Dewey Cox Story") puts the audience squarely the film's suburban Illinois setting even if the movie was shot in California.

John Michael Higgins's perfectly square performance as Principal Wally Snur helps anchor the town's mentality.

Elizabeth is a fish out of water. Her refusal to conform becomes an asset when she learns about a cash prize that goes to the teacher whose class does best on statewide exams. No more classroom screenings of "Dangerous Minds." Instead, Elizabeth goes off the syllabus to make her class read "Animal Farm" and "To Kill a Mockingbird." The problem is she still isn't a very good teacher. Desperate measures involve the comical seduction of school testing official Carl Halibi (played for laughs by Thomas Lennon).

"Bad Teacher" might just attain a bigger cult status than "Bad Santa" if only because it's more shocking to hear filthy lines delivered by Cameron Diaz than by Billy Bob. Diaz's character also has fewer redeeming qualities than Billy Bob's grump with a good heart. "Bad Teacher" acknowledges the baneful greed at the heart of America's obsessive mentality and pokes fun at it. I'll drink to that.

Rated R. 92 mins. (B) (Three Stars - out of five, no halves)

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