Contrary to appearances, ‘‘Dodgeball: A True Underdog Story’’ is not merely a crude mass of scenes in which people are viciously pelted with rubber balls — hard! — in the chest, groin and head. Although, heaven knows, that alone should be enough to satisfy even the most demanding cineaste.

Unbelievably, there's more. Starring Vince Vaughn and Ben Stiller as adversaries in America's most controversial playground game, ‘‘Dodgeball’’ also functions as a rather smart, cutting satire of pro sports, fitness club narcissism and the trite methodologies of populist cinema itself. It's the sort of relentlessly ironic put-on that looks retarded from a distance but reveals certain amusing — even hilarious, I'm almost ashamed to admit — qualities up close.

Vaughn (‘‘Old School’’) is his usual snarky self as Peter La Fleur, a smooth- talking slacker who runs a no-frills, sweat-stained neighborhood gym called Average Joe's. When the gym is scheduled for foreclosure by his bank, Peter gathers together the nerds and crazies who frequent the place and enters a dodgeball tournament in Las Vegas. Grand prize: $50,000, just enough to cover the overdue mortgage. Stiller gives his most howlingly nutty performance since ‘‘Zoolander’’ as Peter's blow-dried rival, White Goodman, an appearance-obsessed fitness fanatic who wants to buy Average Joe's and turn it into a parking lot for Globogym, a slick exercise boutique that features on-site cosmetic surgery.

Attired in a series of flamboyant workout ensembles — with a fussy handlebar moustache that speaks of latent sexual identity issues — Stiller excels in a rare villainous turn, his first since playing the grandma-abusing orderly in "Happy Gilmore." Determined to ruin Peter, White puts together his own, steroid-enhanced dodgeball team — dubbed the ‘‘Purple Cobras’’ — and heads to Vegas, where the tournament is televised on ESPN8, ‘‘the Ocho.’’ Stiller's real-life wife, Christine Taylor (‘‘The Brady Bunch Movie’’), also stars as a dodgeball ringer who defects to Peter's team.

First-time writer-director Rawson Marshall Thurber riffs happily and heartily in this cozy sports ghetto he's created; in possibly the year's funniest scene, Peter and his teammates watch a Roosevelt-era dodgeball info-film that cleanly distills the lusty, Nietzschean thrill of brutalizing the slow and weak.

Thurber isn't above the occasional low-brow gimmick — to wit, the movie is awash in cameos, including appearances by German national treasure David Hasselhoff and cycling legend Lance Armstrong — but at least he exhibits a disarming level of self-awareness about it. As in many bad, formulaic movies, there's a day-saving suitcase of cash that magically materializes at the end. The difference is, this one is helpfully labeled ‘‘deus ex machina.’’