Boys behaving badly is good for once.
The old adage ''What happens in Vegas, stays in Vegas'' has never felt truer than it feels in The Hangover, since no one who partook of the film's central event -- a bachelor party -- can remember anything about it the next morning.
The only things Phil (Bradley Cooper), Stu (The Office's Ed Helms) and Alan (Zach Galifianakis) know for sure on awaking is that there's a chicken roaming their hotel suite. And a precocious baby in the closet. And a full-grown tiger in the bathroom.
Oh, and the evening's honoree -- bridegroom-to-be Doug (Justin Bartha) -- has gone missing, with his wedding a day way.
Structured like a mystery, in which characters retrace their steps to find out how they arrived at their dire predicament, The Hangover has a solid, driving narrative instead of a mere premise, a rarity among raunchy R-rated comedies. The gags come within the context of the story, instead of being loosely connected by it.
Screenwriters Jon Lucas and Scott Moore, more than atoning for that lump of coal Four Christmases, have come up with new and inspired ways for a group of guys to get into trouble during a night of debauchery in that most sinful of cities. Much of what happens in The Hangover isn't exactly plausible, but it is tethered to reality just enough to ring funny anyway.
Director Todd Phillips (Old School, Road Trip), a connoisseur of the infinitely infantile ways in which men can behave when left to their devices, grooves on the unusual chemistry among his seemingly mismatched leads: The slick, straight-arrow Cooper, the responsible Helms and the shaggy, rotund Galifianakis, who often seems to be going off the page and improvising, usually to killer effect (the bit with the baby's funny hand motion was his idea).
The Hangover also features knockout supporting turns by Mike Tyson (playing himself, hilariously) and Ken Jeong, a character actor with a growing track record of leaving an indelible mark via his small roles (he played the prissy king in Role Models and the temperamental doctor in Knocked Up).
Best of all, The Hangover doesn't succumb to the dreaded sentimentality that often weighs down comedies about boys behaving badly, in which lessons are learned, and the characters agree to grow up in the third act (see: Wedding Crashers). The Hangover remains unrepentantly irresponsible and hilarious throughout, culminating with what could be the funniest montage ever to grace a picture's end credits. The summer's first sleeper hit has arrived.
Cast: Bradley Cooper, Ed Helms, Zach Galifianakis, Justin Bartha, Heather Graham, Ken Jeong, Mike Tyson.
Director: Todd Phillips.
Screenwriters: Jon Lucas, Scott Moore.
Producers: Todd Phillips, Dan Goldberg.
A Warner Bros. release. Running time: 99 minutes. Vulgar language, nudity, sexual situations, pervasive raunch and all-around bad behavior. Playing at: area theaters.
Zach Galifianakis, left, Ed Helms, Justin Bartha and Bradley Cooper raise a toast on a Las Vegas rooftop.