The conscientious comedian Steve Coogan has gained what little attention he’s found in this country thanks to his reflexive, chatty roles in Michael Winterbottom’s “24 Hour Party People” and “Tristram Shandy: A Cock and Bull Story,” and maybe, to stateside fans of British television, for his full-bodied portrayal of the deliciously repulsive Alan Partridge. But even fans may not fully recognize him in his new role. “Hamlet 2,” which opens nationally on Friday, finds the actor shorn of his accent and knee-deep in our current brand of homegrown comic manure — namely weak, semi-ironic parody, packed with “South Park”-style explosions of vulgarity, abuse, and self-consciously awful musical numbers.

Dressed in schlub drag, Mr. Coogan plays high school drama teacher Dana Marschz, a talentless lover of capital-A acting and a self-appointed savior of drama. Dana passionately directs stage adaptations of Hollywood movies such as “Erin Brockovich,” but he’s razzed by the school’s pubescent drama critic and threatened with cutbacks. The only possible solution is to mount his opus, “Hamlet 2.” Of course, the only people who can help are his students — contemptuous teens who, being Hispanic, remind him of “Dangerous Minds.” Two devoted theater types also hope to help.

When Dana isn’t inspiring minds, he’s busy losing ground and face with his shrewish wife Brie (Catherine Keener, actually not at her cruelest). But mostly, we see him being obliviously uncool in front of his students and explaining either the finer points of bad drama or the specifics of his “Hamlet 2” abomination. There’s also a dead-on-arrival joke in which Elisabeth Shue plays “herself” as a nurse who has retired from acting and is deeply admired by Dana.

“Hamlet 2” is really one long, rambling run-up to the musical that is prominently featured in the movie’s advertisements, which play up the number “Rock Me Sexy Jesus” as if to whet curiosity for wacky laughs. In fact, the movie feels curiously airless, even off-puttingly flat. Director Andrew Fleming appears at times to think of himself as being above setting up his jokes or shaping the scenes he wrote with “South Park” veteran Pam Brady.

Mr. Coogan doesn’t embarrass himself — “Hamlet 2” is not some waddling turkey that will send him hightailing back to England. But, perhaps because he’s working with someone else’s subpar material, the type of obsessively conceived, character-based comedy with which he has made his reputation isn’t able to bloom. Dana showing up in a caftan to keep his sperm count high feels interchangeable with any number of gags. There’s nothing so dead-on as, say, Alan Partridge’s habit of smuggling an extra-large plate to the buffet at his extended-stay hotel.

Dana is pathetic and overeager, but Mr. Coogan, as if overcompensating to play his American character, retreats from playing at his more British specialty of foot-in-mouth self-consciousness. Sadly, no such riveting dynamic shows up in its stead; the actor seems to impose an aw-shucks limit on truly developing Dana’s foibles and missteps. (There’s also something disorienting about the reconstituted American accent replacing Mr. Coogan’s precise English drawls and twangs.)

The gala presentation of “Hamlet 2” — mounted under the bright lights and fierce words of the press, a baiting ACLU lawyer (Amy Poehler), and school authorities — might hold your attention. That is, unless you’ve seen more than a couple of episodes of “South Park.” If the giddy mood hasn’t gripped you by the time of Jesus’s big 1950s-style teenybopper number, working up the energy to drop your jaw might just be too much.

Throughout “Hamlet 2,” there’s a sense that Mr. Fleming and Ms. Brady hit upon their howler title and then counted on riffing and chortling their way to a strong finish. Certainly, the exhaustively reported fact that Focus Features picked up the movie after its Sundance premiere for $10 million will do little to discourage such screenwriterly salesmanship. “Hamlet 2” is a movie that bets on built-in enthusiasm. Stuffed as it is with drama-class jokes (think “Waiting for Guffman”), that’s not implausible. But Mr. Coogan is better when he can work harder than this.