The guys' trip to Vegas. The bromance of the bachelor party. These are current cultural givens, situations that suggest their own outrageous events without you ever visualizing the final results. It's all sin, shots, and strippers (accent on the strippers). Anyone venturing into such territory - artistically, that is - runs a two-fold risk of failing anticipation and flatly fulfilling expectations. It's within such complicated comedic realities that Old School's Todd Phillips comes to the concept, and he delivers big time. Uproariously funny, with one certified star-making turn among all the anarchy, this pre-marriage road trip turns the events of one night of drunken debauchery into the stuff of movie myth - and you can't help but laugh all the way through.

Doug Billings (Justin Bartha) is getting married in two days, and his best friends Phil Wenneck (Bradley Cooper) and dentist Dr. Stu Price (Ed Helms) are taking him to Vegas for his bachelor party. Unfortunately, the groom's freakish future brother-in-law Alan (Zach Galifianakis) is tagging along as well. With their villa at Caesar's Palace secured, they head up to the hotel roof for a round of shots before hitting the strip. The next morning, Doug is gone and the remaining ‘party’ members awake in a sea of destruction. Stu has lost a tooth. There's a newborn baby in the closet. And there's a real man-eating tiger in the bathroom. Hoping to track down their pal, Phil, Stu, and Alan begin searching. Eventually, they run into Asian gangsters, Mike Tyson, and Stu's quickie stripper bride Jade (Heather Graham), but no Doug. And time is running out before the groom has to walk down the aisle.

The Hangover is a very funny film, the cinematic equivalent of Jell-O shots. It takes the standard notion of a boys' night out and turns it into part gross-out gag fest, part ‘what comes next’ mystery. There is a darkness to Phillips' take on the material, a genuine sense of danger that comes across clearly and often. It doesn't take away from the humor, but it does make the eventual revelations about the night's events all the more unexpected.

But this movie really belongs to longtime stand-up Galifianakis. As Alan, Doug's baggage-riddled soon-to-be relative, this man-purse carrying closeted savant is so unhinged, so completely and utterly disconnected with reality, that he can make even the most ludicrous question ("Is this the 'real' Caesar's palace?") into psychotic haiku. All throughout The Hangover, Phillips turns the lens toward Galifianakis just to see what kind of fever dream dementia will come crawling out of his maw, and the comedian never disappoints. He literally steals the movie away from Cooper and Helms, who are both outstanding as the relative extremes (partier, pragmatist) who come to see the other's particular point of view.

Yet the most important thing about The Hangover is just how side-splitting it is. Phillips piles on the jokes, keeping the comic tension taut and never once letting us come up for air. There are moments of scatological physical shtick as well as a few chosen moments with a welcome ex-champ (indeed, stay for the credits for more outlandish Vegas cameos). In a genre recently overrun by Judd Apatow and his cadre of friends, The Hangover more than holds its own. It's easily one of the funniest films of the year. Bill Gibron