I Love You, Man

South By Southwest has become a prime spot for raucous R-rated comedies to premiere. “Knocked Up” debuted there in 2007, with “Forgetting Sarah Marshall” in 2008, and now here’s “I Love You, Man.” And while it doesn’t bear Judd Apatow’s name as those others do — it was directed and co-written by John Hamburg (“Along Came Polly”) — it certainly has his fingerprints all over it.

Paul Rudd, one of the key players in Apatow’s Frat Pack, stars as Peter Klaven, a Los Angeles realtor who has just proposed marriage to Zooey (Rashida Jones), his perfect, supportive girlfriend. Zooey has a gaggle of female friends with whom she shares every detail of her and Peter’s relationship, but Peter soon realizes he doesn’t have an equivalent. He’s always been a “girlfriend guy,” quick to find romance while letting close male associations slip away. Now that he’s found the love of his life, his lack of friends is a problem: Who will be his best man?

The obvious answer would be his brother, Robbie (Andy Samberg), a gym trainer and a gay dude (he’s definitely a “dude”) who acts as Peter’s confidant. But then we wouldn’t have a movie, would we? Instead, Robbie helps Peter in his quest to make new friends in the hopes that one will prove worthy of best-man status in time for the wedding.

Plausible or not, it has the makings of good comedy. How do adults go about making friends, anyway? It’s even harder than dating — there are ample online opportunities for finding romance, but purely platonic friendships are trickier. Besides, no one believes you when you say that’s all you’re looking for, and men are suspected of being gay if they set out in search of male friends. You’re supposed to already HAVE friends, and to take them for granted. LOOKING for friends? So gay.

The inclusion of an actual gay character is a smart move on Hamburg’s part, as it makes it easy to bring up a topic that might otherwise have lurked uncomfortably in the background. And yes, as Peter arranges “man-dates” with new acquaintances, one of them does get the wrong idea and assume it’s a date-date, complete with post-date kissing. Once THAT’S out of the way, the movie can get back to its examination of straight-male friendships.

Peter eventually finds Sydney (Jason Segel), a freewheeling agent of chaos who lives in a converted garage, has money but no discernible source of income, and eschews attachments of any kind. He’s Kramer to Peter’s Seinfeld (Hamburg’s co-writer, Larry Levin, penned a few episodes of that show), and soon becomes his Tyler Durden, too, teaching him to cut loose and have fun even when there are no ladies around.

Hamburg wisely avoids most of the plot twists you’re expecting, breaking out of the formula and creating something much fresher. He also, however, lets the film amble along without any story conflicts for quite a while. Most of it is funny, but after a while you think, “Shouldn’t something be happening?” Moreover, a subplot with Zooey’s friend Hailey (Sarah Burns) goes nowhere, and J.K. Simmons and Jane Curtin are underused as Peter’s parents.

But Rudd and Segel, who both appeared in “Knocked Up” and “Forgetting Sarah Marshall,” make a fine comic duo, clearly two different types but not one-dimensional stock characters. (Peter, thank goodness, is NOT a stuffy, conservative dork, which would be the obvious choice to complement Sydney’s loopiness.) Rudd, who has generally played smoother, more comfortable guys than this, is hilariously awkward here, a ladies’ man who has no idea how to be a man’s man. In supporting roles, Jaime Pressly and Jon Favreau are terrific as the standard married-couple-who-hate-each-other. For some reason Lou Ferrigno is involved in all this, too.

That loose, semi-improvised style of the Apatow films is present, as are the sweet sentiments embedded in the vulgar jokes. But whenever the adult humor is deployed without any real purpose — when it’s irrelevant to the story, adds nothing to our understanding of the characters, and doesn’t progress the scene — it stands out as cheap. It’s hard to do this sort of thing well, and I’m glad Hamburg and company basically succeed at it.

B (1 hr., 45 min.; R, pervasive harsh profanity, a lot of vulgarity and sexual dialogue.)