Sometimes a mediocre movie features a scene that comes close to justifying the price of admission. By now, most of us are familiar with the “Rock Me, Sexy Jesus” musical number from the Sundance hit Hamlet 2. It shows up in the trailer and TV ads, suggesting that the producers expected big ticket sales from the controversy fired by a Grease-style doo-wop that depicts the Lord as a cool dude with a “swimmer’s bod.”

Cynical, sure. But when the high schoolers of Hamlet 2 and their buffoonish drama teacher (Steve Coogan) finally perform “Rock Me, Sexy Jesus” toward the end of the film, it transcends the culture wars to become a deliriously silly — even joyful — satire of musical-theater conventions. The preceding number, “Raped in the Face,” is pretty good, too — that is, if you aren’t incredibly offended by the concept of a ballad about childhood sexual abuse that’s also a send-up of Andrew Lloyd Webber.

Such creations have a “South Park” feel to them. As it happens, Pam Brady, who co-wrote Hamlet 2 (with director Andrew Fleming), also shared writing credits on South Park: Bigger, Longer, Uncut and Team America: World Police, two films whose creators’ boundless taste for the tasteless was matched by their obvious love for a rousing song-and-dance number.

All that sounds promising. And if Hamlet 2 had devoted more screen-time to the eponymous play-within-a-play, it might have been an outsider comedy classic. Instead, though, Brady and Fleming focus on the playwright, sad-sack teacher Dana Marschz, who assures his students that enthusiasm can compensate for lack of talent because he hopes it’s true. A refugee from Hollywood, where the high point of his acting career was a herpes-medication commercial, Coogan’s character has settled in Tucson, Arizona, where he and his loyal student thespians — all two of them — stage plays in the high school’s “snackatorium.”

When a bunch of non-drama geeks — most of them working-class Latinos — land in his class, Marschz sets out to win them over, just like the heroes of his favorite inspiring-teacher movies. But his quotes from Dead Poets Society earn him less respect than his mercurial fits of rage and obscenity. And he pours all his craziness into the play he pens in an attempt to save his program from imminent budget cuts. Starting with Shakespeare’s Hamlet and a time machine (to resurrect all those dead characters), Hamlet 2 ends up encompassing everything from Sexy Jesus to Hillary Clinton to Jason Bourne to Marschz’s feelings about his dad. It’s like a play written by a 14-year-old on (or off) some very interesting medication.

There’s material here for a rich comedy about American optimism and delusion. As Marschz, British TV star Coogan calls up shades of Timothy Treadwell, a real-life failed actor whose narcissism — and tragic demise — ended up as fodder for Werner Herzog’s documentary Grizzly Man. Like Treadwell in his Alaska footage, the teacher has a mealy-mouthed, Stuart Smalley exterior that lets slip hints of rage and arrogance. He’s trying to be a “nice guy,” but he doesn’t feel nice.

Rather than develop this character, though, the filmmakers milk him for easy laughs. The same is true of almost all the talented people who appear on screen, from Catherine Keener as Marschz’s weary wife to actress Elisabeth Shue — playing herself — to Amy Poehler as an ACLU lawyer who growls that the opposition can suck her balls.

Time after time, the writers reach for such in-your-face humor as a failsafe. But the nonstop naughtiness that earned so many laughs in Team America and Bigger, Longer, Uncut — perhaps because P.C.-baiting, potty-mouthed cartoons and marionettes are just plain funny — doesn’t suffice in a live-action film. With the possible exception of those inspired musical numbers, Hamlet 2 never rises to any new heights of outrageousness, nor does it have much to say. In the end, it’s one of those movies that sounds a lot more clever when you narrate it to your friends than it was on the screen.