rated R

There are few cinematic meet-cutes that involve dissecting the dynamics of a guy who tries to sneak out a fart in front of his new girlfriend, but that’s exactly how Peter Klaven and Sydney Fife meet in “I Love You, Man.” In this case, Sydney is not a cute, perky blonde but a shambling, scruffy guy sent by fate to instruct Peter on the ways of being a dude. It turns out that a budding bromance is a lot funnier than any romantic courtship, and while “I Love You, Man” is plenty funny, it’s always at odds with the romantic comedy tropes it tries to both adhere to and subvert.

Paul Rudd is Peter Klaven, a career-driven real estate agent who, according to his family, has always been a “girlfriend guy.” That’s great news for Zooey (Rashida Jones), Peter’s new fiancée, but it doesn’t bode well for the wedding party, which will be bereft of a best man. And so Peter’s family and Zooey set him up on a series of increasingly awkward man dates, putting the oft-uncomfortable Peter in a series of increasingly strained friendship scenarios. Added to the pressure of finding a fellow dude to be friends with is Peter’s inability to sell Lou “The Incredible Hulk” Ferrigno’s home in the Hollywood hills. Peter needs the commission on the sale to pay for the wedding, but his timid sales tactics can’t attract a buyer.

Enter Jason Segel as Sydney Fife, a shrewd, quick-thinking slacker who hits up open houses looking for middle-aged divorcees to bed. Sydney gives Peter some sales tips, grabs some complementary food and hits the road, but soon enough, the two are drinking beers, jamming out to Rush and acting like best buds.

It wouldn’t be a romantic comedy if complications didn’t ensue, and so things must go awry, even in a bromance like this. And it’s when “I Love You, Man” tries to awkwardly shoehorn old rom-com clichés onto an otherwise perfectly enjoyable story that the movie drags. The first few “man dates” Peter goes on play out predictably, and though the guys he’s paired with are awesome (“The State” alums Thomas Lennon and Joe Lo Truglio), the scenarios are trite. The same goes for the ending, during which Peter has some doubts about the friendship. Peter and Sydney’s comradeship is so natural and easy that the last-minute kink seems grossly manufactured and inconsistent with the characters. (As a side note, there’s also a lot of annoying product placement in “I Love You, Man,” particularly for Apple. Did we really need so many conspicuous iPhone shots?)

But Rudd and Segel handle even the weak moments in the script with ease, and a lot of the fun in watching “I Love You, Man” comes from watching the two leads just play off each other. In a way, they’re both playing against type—the snarky self-assuredness Rudd brought to last year’s “Role Models” is gone, replaced with a charming awkwardness and quirky penchant for mumbling nonsense words and badly imitating accents. Meanwhile, the bare emotional vulnerability (and full-frontal nudity) that Segel brought to “Forgetting Sarah Marshall” is replaced with a lackadaisical confidence that’s suave but never off-putting.

They’re two genuinely cool guys, though only one of them knows it, and that interplay gives the movie its biggest laughs. After first meeting, they come up with nicknames for one another—Sydney scores with “Pistol,” in honor of basketball star “Pistol” Pete Maravich, while Peter pulls out “Joben,” a non sequitur that he quickly apologizes for. Rudd and Segel are great leads, and based on their performances here, they’ll only get better.

The rest of the cast is just as good. In fact, writer/director John Hamburg has almost too much talent to work with. Andy Samberg, J.K. Simmons and Jane Curtain, three performers who could easily carry their own comedies, all fill in here as Peter’s family members, and Jamie Pressley and Jon Favreau have a good turn as Zooey’s endearingly obnoxious married friends. For the most part, Hamburg lets the characters just be themselves, relying more on dialogue and interaction than gross-out moments (save for one unexpectedly funny scene at a tense poker game) to build laughs. When it comes to making new friends, after all, being yourself is always best—a lesson that, for the most part, “I Love You, Man” heeds well.