Peter is so tuned in to his girl, Zooey (Rashida Jones), that when they get engaged, she promptly calls her three best friends. But the only person on his speed-dial is . . . Mom. While planning their wedding, it hits him: He lacks a pal to be his best man.
Panicked when he overhears Zooey's bud say she doesn't trust a guy without friends, Peter reluctantly commences to audition candidates.
If a good man is hard to find, a best man is hardest. In hopes of meeting one, Peter endures a series of poker nights, drinking games, and man-dates. He'd rather be confecting treats for Zooey's hen parties.
That's when Sydney (Jason Segel), disheveled and uncensored as Peter is fastidious and discreet, bounds into Peter's life. Like an alley cat, Sydney - who claims to be an investor - shows house cat Peter how to get out, get down, and man up.
ILYM is the comedy that Rudd lovers have been waiting for since he first charmed us silly in Clueless. It explores both the dweeby and heartthrobby sides of this guy whose crooked smile fails to mask his social anxiety.
Rudd makes Peter's awkward attempts to be cool a kind of grace. He urgently communicates what it costs for a tightly wound guy to unwind: It makes him emotionally naked. Rudd makes you wince in sympathy with this guy whose only brush with coolness is with his freezer.
As Sydney, Segel - the shambling, deadpan star of Forgetting Sarah Marshall - has the key to opening up his locked-down friend: Draw him out. Sydney, who has an outrageously insensitive streak, is very good at one-to-one.
The caveman and the metrosexual enjoy (purely platonic) walks on the beach, bromantic dinners where they bond over their favorite band (Rush) or favorite food (fish tacos).
Often, they repair to Sydney's "man cave," an adolescent boy's fantasy lair furnished with adult-male toys and Sydney's stern-eyed pug, Anwar Sadat, named for its resemblance to the late Egyptian president.
Unsurprisingly, the film - directed by John Hamburg (Along Came Polly) and cowritten by Hamburg and Larry Levin - is on the raunchy side, with candid discussions of bathroom and bedroom activities.
Surprisingly, it also boasts keen perceptions about friendships (female and male) and how these extramarital bonds can nourish or starve a marriage. Zooey thinks nothing of sharing intimate relationship details with her friends, but she is unnerved when Peter does the same with Sydney.
With the exception of a mucho macho type comically played by the growling Jon Favreau, the film likes all of its characters - male, female, straight, gay, sensitive, and insensitive - rare in a Hollywood production. Among those buddy films lately called "bromances," ILYM is both the best friend and best man.
Contact movie critic Carrie Rickey at 215-854-5402 or firstname.lastname@example.org. Read her blog, Flickgrrl, at http://www.philly.com/philly/blogs/flickgrrl/.