No one fornicates with a pie or gets super-glued to their privates in American Wedding, the third and final installment of the American Pie trilogy, but there’s plenty of penis-related disasters going on in director Jesse Dylan’s ode to friendship, fidelity and clandestine fellatio. Working from its predecessors’ schizophrenic template--in which the film’s sweetly sentimental old-fashioned values are cloaked beneath the guise of infantile gross-out humor--the film charts the predictably wacky procession of obstacles pie-lover Jim (Jason Biggs) and band camp nympho Michelle (Alyson Hannigan) must overcome on their way to the altar. The arrival of Michelle’s straight-laced parents Harold (a wasted Fred Willard) and Mary (Deborah Rush) sends Jim into paroxysms of spastic jumpiness, and it doesn’t take long before his preordained humiliation in front of these future relatives-in-law occurs in the form of both a public inter-species orgy and a stripper-infested dinner party.

But since the naïve Jim’s self-inflicted embarrassments have long since grown stale, the filmmakers quickly lose interest in Jim and Michelle’s holy union and turn the film into a showcase for Seann William Scott’s puerile Steve Stifler. Scott, a one-note comedian who has nonetheless mastered the art of combining self-conscious mugging for the camera with rampant (albeit sweet-natured) vulgarity, turns this Wedding into the Stifler Show. Stifler is unwanted at the festivities because of his reputation as a thoughtless, ingratiating troublemaker, but that doesn’t stop the loudmouthed clown from crashing the party, trying to seduce Michelle’s sister Cadence (January Jones) and making a regular ass of himself. When he winds up in a gay bar, Stifler engages in a dancing duel with a muscular stud, each taking turns preening and prancing to ‘80s staples like “Maniac” and “Heaven is a Place on Earth.” The stereotypical characterization of gays as flamboyant queens decked out in puffy shirts and backdoor-accessible pants would be more insulting if it didn’t point to Stifler’s infatuation with men’s sexual organs marks him as a closeted queen himself.

If this unnecessary sequel feels hijacked by Stifler’s periodically revolting antics, at least his hyper-macho insanity lends the film a spark that’s otherwise completely lacking from the rest of the mundane nuptials. Although the filmmakers seem uninterested in Jim and Michelle’s big day, they’re altogether flummoxed as to how to incorporate Jim’s boring buddies Finch (Eddie Kay Thomas) and Kevin (Thomas Ian Nicholas) into the story. Furthermore, Adam Herz’s script doesn’t even bother explaining the glaring absences of Pie regulars Chris Klein, Mena Suvari, Natasha Lyonne and Tara Reid. Eating dog droppings, shaving one’s pubic hair, and the inappropriate use of sex toys are counterbalanced by Jim and his forthright dad (Eugene Levy) earnestly discussing marriage and sex, but it’s no longer all that funny to hear Levy candidly opine on topics like a woman’s period.

Traditional morality hidden under a juvenile infatuation with excrement and big boobs has always been the films’ bread and butter, but American Wedding (more shamelessly than its predecessors) only perfunctorily pays lip service to wholesomeness while enthusiastically indulging in its disgusting pranks. It’s a clear sign that the filmmakers’ creative well has run dry, but it’s also an honest turn for a series that owes its success less to smarmy platitudes than to the humorlessly infantile image of a teenager having sex with a gooey desert. Stifler’s mildly infectious idiocy provides sporadic chuckles, but I’m still ready for a quick divorce from this long-in-the-tooth engagement.