There is a late scene in "The Hangover" where henpecked dentist Stu Price (Ed Helms), finally gaining a backbone, stands up to his ball-busting fiancée (Rachael Harris) and tells her, "You are such a bad person, right down to the core." Those words basically could describe the bulk of the film's characters. If not rotten through and through, most of them are obnoxious beyond words and nearly insufferable to be around. So is the movie, an R-rated comedy in the smarmy, wildly overpraised vein of 2005's "Wedding Crashers" and 2009's "I Love You, Man" that is so pleased with itself it has left out the key ingredients—wit, sharp comic timing, a twisting of expectations—necessary for truly humorous material.

Doug (Justin Bartha) is days away from marrying Tracy (Sasha Barrese), and that can only mean one thing: it's time for his bachelor party. Dutifully, best friends Phil (Bradley Cooper) and Stu, along with Tracy's socially awkward brother Alan (Zach Galifianakis), treat Doug to a night in Vegas. No sooner have they checked into their hotel suite and toasted drinks on the roof that they suddenly wake up many hours later with no recollection of what happened the night before. There's a growling tiger in the bathroom, a baby in the closet, a hospital band on Phil's wrist, a wedding ring on Stu's finger, a missing tooth in Stu's mouth, and a groom who is MIA. With time ticking down, Phil, Stu and Alan must attempt to retrace their steps in order to find Doug and right their wrongs.

"The Hangover" is 100 minutes of actors hamming it up in mechanically orchestrated poses and predictable situations, not helped by a story that goes virtually nowhere until an end-credits collection of snapshot photos. These serve to fill in the blanks that the rest of the movie was too lazy to answer, coming off as a desperate last-gasp from a movie that hasn't delivered the imagination, cleverness and laughs promised by the premise. It's all supposed to be sheer hilarity at its most wacky and wild, and there are few things worse than a film that presumptuously thinks it is something it's not.

Director Todd Phillips (2006's "School for Scoundrels") and screenwriters Jon Lucas and Scott Moore (2009's "Ghosts of Girlfriends Past") are stuck on autopilot here, sucking the life out of a potentially funny plot. The problems are many, starting with a city-wide hunt for Doug that offers some vague clues to what went down, all of their inferences a great deal more entertaining than the aftermath investigation. Were a sequel to concentrate on the debaucherous night in question, now that might be something to see. This time around, the tired jokes land with such a thud that one wonders what was supposed to be amusing in the first place.

The male foursome at the picture's center reveal themselves to be immature, irresponsible and annoying from the get-go—teacher Phil ignores his students and calls them nerds while still on school grounds; Stu is picked up at his house by the others, who loudly call him "Dr. Faggot;" upon receiving a compliment on their car at a gas station, Alan is needlessly belligerent to the kindly old man and chases him away—and are impossible to like thereafter. Their later criminal mischief, including destruction of property, fraud, child endangerment, and the theft of a police car, doesn't exactly help their cause for sympathy. Other gags, like the exploitative sight of an elderly hospital patient's saggy backside, a limp episode involving a taser and a roomful of kids, and the appearance of Mike Tyson for the purpose of singing Phil Collins' "In the Air Tonight" before punching Alan's lights out, are dead ends that lack a point or, at the very least, a payoff.

Of the actors, Zach Galifianakis (2008's "What Happens in Vegas") and Ed Helms (2008's "Semi-Pro"), as Alan and Stu, are certainly more adept at comedy than Bradley Cooper (2009's "He's Just Not That Into You") and Justin Bartha (2007's "National Treasure: Book of Secrets"). As Phil and Doug, Cooper and Bartha look cold, irritated and oddly apathetic. They are badly miscast. And while it is nice to see the lovely Heather Graham (2006's "Bobby") in anything, surely she deserves better than a half-handful of scenes as a stripper with a heart of gold. On the upside, her character of Jade is the only sweet-natured presence around and worth mentioning for this fact alone. Otherwise, "The Hangover" goes down about as easily as Benadryl spiked with tequila. Flatly photographed besides (the glittering neon and sun-blazing asphalt of Las Vegas have never looked so unappealing), it's a glib, drab, fatally unfunny study in mean-spirited mediocrity.