“Jackass: The Movie,” the big-screen version of the popular MTV series about a troupe of moronic misfits and their destructive (and self-destructive) pranks, is everything its detractors claim it to be. It is rude, crude, offensive, disgusting and incredibly infantile. It treats mindless chaotic behavior and harmful self-mutilation as fodder for comic coolness. It is basically a stain on our culture, a symbol of the degeneration of popular entertainment.

All these negative assertions cannot be denied. But the critics always forget to add that the film (and its source show) is clutch-your-sides, roll-on-the-floor, hyperventilate-and-pee-yourself-at-the-exact-same-moment, uproariously funny.

Maybe these proud, self-proclaimed “Jackass” haters really just do not agree with this assessment. Maybe they were just having a bad day when they decided to blame a dopey freak like Johnny Knoxville for a child’s brilliant plan to light himself on fire. Or maybe they have too many whiny constituents rammed up their rears. Whatever the reason, “Jackass: The Movie” is what it is, and never pretends to be otherwise. It is a cleverly simplistic, utterly plotless romp that provides a nice alternative to the onslaught of high-minded serious pictures battling to be Oscar’s annual whore.

How can anyone hate a movie in which a man eats a snow cone covered in his own urine? It is an especially repulsive moment in a nauseating film, but the underlying charm of the concept is that we are watching a bunch of dimwits who are willing to do almost anything to entertain us. These guys are desperate, pathetic, and talentless, but all they really want is to be amateur comedians (and rich and famous ones at that). Ultimately, the audience is really laughing at the revelation that there are people who are willing to engage in such idiocy.

But these jackasses are no ordinary bunch of boneheads. They are fools with an awareness of their ridiculousness. The film opens with an out-of-control, slow-motion slugfest on a careening shopping cart set to a tense operatic score, a faux-epic journey that establishes the movie’s tongue-in-cheek tone. What follows is the simple “Jackass” formula: a series of pranks and gags that raise the stakes until it reaches an “I can’t believe he did that” crescendo utterly defying the limits of logical human behavior.

Each skit is very funny in its own right. Ingeniously simple highlights include the relentless disruption of an intense golf game with a bullhorn, the demolition of a rental car and subsequent refusal to provide compensation, the snorting of a spicy Japanese side dish, and one jackass’s decision to move his bowels on a toilet in the middle of a store that sells, what else, toilets. These scenarios draw added humor from the priceless reactions that the “normal” human witnesses provide.

It is the movie’s overall structure that lifts the antics to mindless comic bliss. While most big-screen adaptations of short-format sketches — think every bad SNL takeoff — strain the story line to fit the requisite feature-length, “Jackass” is faithful to its plotless origins while cohering surprisingly well. It mixes short non sequiturs — such as a fearless dwarf named “Wee Man” kicking himself in the head — with recurring bits, such as one jackass’ irrepressible drive to disturb his hapless parents by putting an alligator in their kitchen and lighting fireworks in their bedroom.

Fearless leader Knoxville takes the heaviest beating for the sake of his “craft.” He is shot in the stomach by a powerful blank pellet, bitten on the nipple by a baby crocodile, and beaten severely by a heavy professional wrestler. His willingness to endure such agony makes “Jackass” more than just a collection of loosely strung together gross-out gags. It becomes a revealing study of the male ego, the “I double dare you” effect taken to unthinkable and increasingly humorous extremes.

But mostly “Jackass: The Movie” succeeds because its band of players appear to be having such a darn good time. They want to entertain us, yet to an even greater extent, they just want to entertain each other. You can’t escape the feeling that this “movie” is just some buddies hanging out and re-enacting their youthful immaturity. They have made a successful career out of their own repressed inner children, and they could care less about the reaction of some snooty senator. It is this base and simple realization of the American dream that may be the movie’s funniest joke of all.