C-

Anyone looking for a close approximation of the queasy mixture of the nasty and the sweet familiar from mediocre Farrelly Brothers movies (as opposed to their good early stuff like “There’s Something About Mary” and “Kingpin”) is directed to this raucous but largely mirthless example from writer Adam “Tex” Davis and director Roger Kumble (“The Sweetest Thing”). “Just Friends” has a few stray laughs, mostly courtesy of the supporting cast, but for the most part it’s utterly predictable and often downright unpleasant.

The premise: Chris Brander (Ryan Reynolds, initially seen in what looks like Martin Short’s castoff Jiminy Glick fat suit) is a sweet-natured but obese high-school senior in love with classmate Jamie Palamino (Amy Smart). But she thinks of him merely as her best pal, and at a graduation party he’s humiliated when his secret admirer status is accidentally revealed. Fast forward a decade and Chris has been transformed into a slimmed-down Hollywood record executive; but he’s changed in other ways as well, becoming a womanizing chauvinist pig. On a flight with a former flame, the cracked pop diva Samantha Jones (Anna Faris) whom his boss KC (Stephen Root) has ordered him to re-sign with the company, a malfunction forces the plane down in his New Jersey home town, and he and the berserk Ms. Jones decide to stay with his brainless mom Carol (Julie Hagerty) and younger brother Mike (Christopher Marquette), who divides his time between ogling Samantha and tormenting Chris. While fobbing off the clinging Samantha on Mike, Chris decides to reconnect with Jamie–not to romance her so much as to impress her with what a success he’s become. Of course his love is rekindled even as he turns her completely off with his smarmy self-importance, and to make matters worse another old high school suitor shows up in the form of Dusty Dinkelman (Chris Klein), who used to be a pock-marked doofus but has turned into an apparently sensitive paramedic who’s now smooth in every respect. What follows is a succession of frantic, and frequently brutal, slapstick episodes, in which Chris (and Samantha too) are repeatedly abused (the worst unquestionably coming when Chris is called on to play hockey with a bunch of kids, with very unfortunate results). And when that sort of mistreatment isn’t being ladled on the characters, the running-time is taken up by supposedly sentimental scenes featuring Jamie, purportedly funny rough-housing between Chris and Mike, or the unsurprising revelation that Dusty isn’t the choirboy he seems. The ending, of course, is never in doubt.

The good news? Smart is an engaging presence who makes Jamie seem almost real (though not very funny), and Marquette’s goofy brother routine will probably appeal to the frat-boy crowd. But Reynold’s Van Wilder persona, which we suffered through as recently as “Waiting,” does not improve with repetition, and Faris’ dumb but demanding blonde bit quickly grows tiresome; this sort of shrill riff on California self-absorption is better when done a mite less broadly and continuously than this. As for Klein, his presence does little other than to remind us of the Farrelly similarity–a comparison that is not helpful. And veterans Hagerty and Root are pretty much wasted in throwaway parts.

“Just Friends” is reasonably well made–the wintry locations feel authentically snowy and frigid, and they’re decently photographed by Anthony B. Richmond. The other tech credits are above par, too. But to borrow from the picture’s Christmastime motif, the result is like a package that’s attractively wrapped and ribboned but proves to contain a frayed hand-me-down. “Just Friends” is just another failed attempt to match the mood of the early Farrellys–something even the brothers don’t appear to be able to do anymore.