Few moviegoing experiences are as excruciating as watching two gifted comics struggle with terrible material. Dinner for Schmucks, therefore, is like an inescapable get-together dominated by humorless palaver and juvenile games, courtesy of people who seem amusing enough at the office but are unbearable for stretches at a time. But the guilty parties in this case are Steve Carell and Paul Rudd—and damn, it’s hard to watch them squirm.

“Inspired by” the French film Le Dîner de Cons, this comedy directed by Jay Roach (Austin Powers, Meet the Fockers) pits a reluctant asshole against an enthusiastic idiot. The former is Tim (Rudd), a white-collar ladder-climber who feels that, if he wants a promotion, he must attend his boss’ regular “Dinner for Winners”—which actually is a competition to see who can bring the biggest moron. Tim’s good-guy conscience is further reflected by his good-girl girlfriend, Julie (Stephanie Szostak), who knee-jerkingly leaves their apartment—and seemingly, him—when he shows a glimmer of willingness to go along with the cruel gag. She doesn’t even know him anymore!

Tim is ready to wriggle out of the commitment when he hits Barry (Carell) in a texting-while-driving accident. (Take note, kids!) When Barry picks up a dead mouse to add to his lavish dioramas—his “mousterpieces”—and backwardly thinks he needs to bribe Tim to keep insurance out of the incident, Tim believes he’s received a sign. He invites Barry to the party the next night. But Barry shows up at his apartment that evening, and immediately begins his campaign of destruction.

With the exception of bathroom gags (which relatively fledgling scripters David Guion and Michael Handelman mercifully avoid), easily fixable misunderstandings and mouth-breathing whoopsies are about the lowest forms of humor. And Dinner for Schmucks is full of both. Take Barry’s absurdly unbelievable IMing with a stalker of Tim—Barry sits in front of Tim’s computer and giddily gives out his address once the conversation escalates from flirtatious to graphic. And when Tim allows Barry to stay the night and leaves for work the next morning—with plenty of other mishaps occurring in between—he grabs Barry’s phone instead of his own. As a result Barry finds the details of an important business lunch that he then blows with the intention of helping Tim. This goes on. And on.

There’s also Kieran, an eccentric artist played by Jemaine Clement, whose show Julie is curating. He’s shaggy-haired, egotistical, and plenty weird—and was funnier when named Aldous Snow, aka Russell Brand’s nearly identical rock star in Forgetting Sarah Marshall and Get Him to the Greek. The thieving is shameless. And the main laff contribution of Zach Galifianakis, who plays Barry’s eccentric IRS colleague, is that he wears a dickey. Will this PG-13 film’s target audience even know what that is?

It’s up to Carell and Rudd to carry the film, and their strain in doing so are obvious. Although there are small laughs here and there—it seems the pair’s charisma can’t completely be quashed—Barry is too much of a buffoon and Tim too exasperated a straight man for the premise to work. (Rudd is an even more serious version of his I Love You, Man character, with Szostak a practical twin of that film’s Rashida Jones.) The freaks at the last-chapter dinner party are more entertaining, but by then you’re weary.

Of course, there’s a heartwarming message to the story, instigated by overheard conversations in which people either get their feelings hurt or find out how much they mean to someone. Lessons are learned! In the end, however, the true stars of the show are Barry’s elaborate dioramas, which feature impeccably dressed mice in lovely first-date-like outdoor settings that later play out Barry’s sad secret. But pretty rodents belong in comedy as much as dickeys belong on modern businessmen.