THEY ARE unarmed, those who have taken up the critic's path without a preliminary reading of Richard Brinsley Sheridan's 1779 play The Critic. One character, Puff, gave his name to the "puff piece," so familiar in journalism, either print or electronic. Puff lays out the field: "The puff direct, the puff preliminary, the puff collateral, the puff collusive and the puff oblique, or puff by implication"—the last, today, is popularly known as the "name check."

Sheridan also observed how the puffer sometimes scolds and puffs at the same time. Today's light ironist displays this behavior in his natural habitat: newspapers and magazines. Modern puffers adopt what Puff himself called "a countenance [face] of smiling censure and tender reproach" as they puff the living daylights out of some half-baked film or some half-talented performer.

Puffers will be mistaken if they believe that School for Scoundrels is based on Sheridan's best-known play, The School for Scandal (1777). Director Todd Phillips seemed to think so: why else does one scene take place in front of the brass plaque of the Sheridan Arms Apartments?

Actually, the new School for Scoundrels is extracted from a 1960 British movie featuring gap-toothed swine Terry-Thomas as the school's "professor." The books this English comedy sources were real-life self-help texts, the One-Upmanship series by Stephen Potter, who suggested power plays for the meek British.

The remake provides some big laughs, especially since the self-help industry has only swollen since Potter's day. This time, the school in question is a clandestine class held in a Manhattan Learning Annex building. It's taught by the Werner Erhardish "Dr. P," a bilious Billy Bob Thornton in sun-tan makeup and toupee. He passes out advice on the best ways to lie and manipulate and keeps an enforcer (Michael Clarke Duncan) to make sure that the male worms in his class don't attack him.

Roger (Jon Heder) becomes the best student, dominating an every-man-for-himself paintball game. Seeing his pupil succeed rouses Dr. P's alpha-dog instincts, and he decides to go after the girl of Roger's dreams, Amanda (Jacinda Barrett). "An easy take-down," Dr. P claims, and he proceeds to impersonate a bereaved widower learning to love again. Meanwhile, Roger turns the unscrupulousness he has learned against his teacher.

It is now clear why Napoleon Dynamite was a success. It was not the director, Jared Hess, but the star. Heder is part of an eternal golden braid of twerpiness that connects him to Woody Allen and Don Knotts and Eddie Bracken. Heder's Roger has a pitiful comic job (male meter maid), and a tendency to faint from panic attacks. Not every comic actor can pitch a faint well without the audience fearing for him.

Heder is gangly, and his beaverish teeth look like the results of some expensive orthodontics. His chinlessness and chestlessness make him the perfect bully magnet. He is humbled at work, where his boss (Luis Guzmán) treats him with gentle regret, like a baby sitter might treat a stinking and backward child. In his hallway, Amanda's housemate (she-devil Sarah Silverman) provides zesty emasculating lines, perfect for countering the potential too-cuteness of Heder's fool. It's far funnier than the Happy Tree Friends to see Silverman's rabid chipmunk savaging Heder's neutered squirrel.

Barrett, an actress who tends to fade into the drapes, keeps her Aus accent; she is wooly here, swathed in earth-toned sweaters, and has the maternal nebbishbess that would make her logically fall for such a twit.

Roger's idea of a dashing stunt to impress Amanda is liberating the lobsters from a restaurant's seafood tank and tossing them into the East River. That ploy has been considered adorable in so many serious romantic comedies, but it is far wittier in something screwball. Heder, like all great twerps, is most funny when he's being most suave. Preparing himself to see Amanda, Heder recalls Woody Allen in Bananas, when Allen was driving to a date, rehearsing a dinnertime anecdote about the roots of his name, Fielding: "Fielding, from the Latin meaning 'strong,' or 'with strength' ... you'll come to lean on that strength after a while," and the camera pulled back to reveal Fielding's chariot, a crunched, one-eyed Volkswagen Beetle.

A documentary filmmaker now turning to features, director Phillips (Old School) is becoming more sophisticated, learning to use a strike below the belt as seasoning, instead of as the essence of the comedy. And Phillips has structured the comedy, which doesn't get done nearly enough: there are little things, like making sure the villain is primping himself in the mirror in the instant right before unseen hands reach around and chloroform him.

Phillips also wisely uses David Cross and Ben Stiller in little doses. (Stiller plays a male cat-lady with Grenada war syndrome.) The two black street bullies seem borderline racist, perhaps in contrast with Heder's comedic whiteness. Otherwise there's nothing in School for Scoundrels to cite with either smiling censure or tender reproach.

School for Scoundrels (PG-13), directed by Todd Phillips, written by Phillips and Scot Armstrong, photographed by Jonathan Brown and starring Billy Bob Thornton and Jon Heder, opens Sept. 29.

Send a letter to the editor about this story.