Zac Efron gives a comparatively restrained, likable performance in Jake Szymanski’s “Mike and Dave Need Wedding Dates.” That pretty much exhausts the virtues of the ultra-raunchy comedy, a movie of sub-Apatow quality that mines the wacky wedding territory such crass farces as “Wedding Crashers,” “Bridesmaids” and the “Hangover” movies have found lucrative in the past, only to come up empty. Of course, the operative word is “comparatively,” since Efron comes off decently because everything and everyone around him is so awful. (The situation might remind you of “Dirty Grandpa,” in which he was hardly a prize, but got a pass because we were all busy watching Robert De Niro besmirching a mostly illustrious career.)

Here Efron plays Dave Stangle, a dim-bulb heartthrob who lives with his even dumber brother Mike (Adam Devine), with whom he also partners in some sort of wholesale-liquor business. The two are would-be hucksters and frantic girl-chasers, and have habitually come to family gatherings stag—and ruined them by hitting on the women in attendance and generally acting like the numbskulls they are. Now their younger sister Jeanie (Sugar Lyn Beard) is planning a destination wedding in Hawaii—she’s marrying a rotund, endlessly tolerant fellow named Eric (Sam Richardson)—and their father Burt (Stephen Root) lays down the law: they have to being dates.

Where to find nice girls—not the sort they’re accustomed to—for such an outing? The boys go to Craigslist to advertise for candidates, and even appear on “The Wendy Williams Show” to explain their predicament. Thousands of girls respond, but the eventual winners are a couple of ultra-vulgar, alcoholic druggies, Alice (Anna Kendrick) and Tatiana ( Aubrey Plaza), who do their best to impersonate respectable career women (a teacher, a broker) and arrange an “accidental” meeting with the guys to persuade them they’re the perfect choices. The scheme works like a charm, of course; Mike and Dave (characters based on real fellows who wrote about their dating life) are an incredibly stupid pair, after all, and easily tricked.

Things do not go well in Hawaii, of course, as the girls find it increasingly difficult to keep up their pose. Alice is repeatedly reminded of her own recent bad wedding experience—her fiancé dumped her at the altar—while Tatiana fends off Mike’s advances, as well as those of his extravagantly butch (and equally competitive), well-heeled and well-connected cousin Terry (Alice Wetterlund, doing good work but in a shockingly unpleasant stereotype of the predatory lesbian). But actual disaster strikes when the foursome, plus the bride-and groom-to-be, go off on a Jurassic Park ATV tour, during which Mike, trying to duplicate one of Tatiana’s dune buggy stunts, instead crashes into his sister. As if that weren’t bad enough, Alice tries to make up for the faux pas by arranging a special massage for disfigured Jeanie by a masseur named Keanu (Kumail Nanjiani)—a gruesomely extended sequence that doesn’t so much test the bounds of good taste as simply rip them to shreds. That stunt puts the whole wedding in jeopardy, though of course Mike and Dave and Alice and Tatiana work together to put Humpty Dumpty back together again—and link properly up themselves.

One can imagine how cleverly the premise behind this script might have been worked out by somebody like Neil Simon or Elaine May back in the day when wit and comic craftsmanship were still in vogue in Hollywood. Nowadays, however, vulgarity reigns supreme, and the writing in “Mike and Dave” seems based on the assumption that the only things today’s audiences will respond to are stupid characters doing idiotic things while engaging in crude conversation. The sole distinction is has to offer is that, instead of concentrating on an all-male (“Hangover”) or all-female (“Bridesmaids”) group of dingbats, it provides obnoxious nincompoops on both sides of the gender divide. Whether Mike and Dave or Alice and Tatiana are the more reprehensible examples of humanity is about the only subject of post-screening debate the movie invites.

Of course, one could also discuss which of the stars comes across as the most irritating. As noted, Efron, basically playing straight man, gets a pass, but Devine certainly doesn’t: he seems to be trying to clinch the Jerry Lewis Lifetime Achievement Award for Ferocious Mugging in a mere two hours. Of the women, Plaza, with her air of Queen Attitude, quickly becomes an aggressive bore. But Kendrick might be the greater disappointment simply because her previous work has shown she’s a capable comedienne whose talent is totally wasted here. The supporting cast try their best to deal with the indignities they’re compelled to suffer, but it’s in a lost cause. And the technical team doesn’t even seem to try: for a picture with a Hawaiian setting, “Mike and Dave,” shot by Matthew Clark, doesn’t boast a very attractive look.

There may be worse comedies than “Mike and Dave” this year—but one fervently hopes not.