Before The Slammin' Salmon, I wouldn't have called myself a fan of the boys from the Broken Lizard comedy troupe, though I have some mild, slightly embarrassed affection for Super Troopers and Club Dread. But Salmon is 90 minutes of truly inspired comic mayhem. With valuable assists from the rest of their cast, Broken Lizard has crafted the funniest film of SXSW – and they had some fine competition. I know I said that you can't trust me, but trust me: this is great stuff.

Broken Lizard is Jay Chandrasekhar, Steve Lemme, Paul Soter, Erik Stolhanske and Kevin Heffernan. Heffernan directed and the entire troupe is credited for the screenplay. But in a shrewd move, The Slammin' Salmon revolves around an outsider: Michael Clarke Duncan, who plays a boxer-turned-restaurant owner named Cleon Salmon, a.k.a. "The Champ." In the best comedy tradition, the Champ combines dim-witted cluelessness with peerless confidence. That, combined with his enormous size, puts his employees in mortal fear of his wrath. So when, one evening, he announces that the waiter with the most sales gets $10,000 while the loser gets a "broken rib sandwich," the waitstaff – led by their officious manager (Heffernan) – step to.

The Broken Lizard guys have always had a flair for chaos, but momentum between the comic climaxes has been known to flag. Here, the restaurant setting provides a strong structure, with the action shifting from the dining room, where the increasingly desperate waiters attempt to milk a rotating crop of customers for as much money as possible, to behind the scenes, where the competition frequently degenerates into surprisingly funny slapstick hijinks. A sales leaderboard tracks the action Glengarry Glen Ross-style, and indeed, Salmon can't resist a knowingly out-of-place reference to that film (though it ignores a more recent parallel, Waiting).

What's most impressive about The Slammin' Salmon is the way the characters are drawn. They don't resemble human beings, except loosely: "Nuts" (Chandrasekhar) is utterly insane and knows it, and tends to run around sans pants when he goes off his meds; Conor (Steve Lemme) spent two weeks in the cast of "CFI: Hotlanta" before being fired because he got a nose job that undermined the script's jokes about his character's huge schnoz. Though obviously absurd, they develop and behave in ways that make sense rather than acting arbitrarily at the whim of the screenwriters. The jokes emerge logically from what we know about the characters. It's painstaking work; the somewhat fly-by-night feel of Broken Lizard's other films appears to be a thing of the past.

But what makes The Slammin' Salmon really hum is Broken Lizard's singular, goofy, off-the-wall sense of humor, refined and sharpened from their prior efforts. If you didn't think the line "How are all of you feline this evening?" could ever be funny, you were so, so wrong. At the center of it all, improbably, is Michael Clarke Duncan, who turns out to be better than anyone on the planet at playing a hulking, self-absorbed buffoon. He only shows up occasionally, but has so much presence and conviction that the movie gains even more momentum when he's on screen. As those who saw Talladega Nights may have suspected, the man is a comic force of nature. He's finally gotten a smarter, richer film in which to prove it.