The Hangover is a mystery tale about three guys following up on the few clues they have about a night of debauchery in Las Vegas. Phil (Bradley Cooper), the suave, handsome one, is wearing a hospital bracelet. Stu (Ed Helms), the dorky dentist, is missing a tooth. Alan (Zach Galifianakis), the borderline-retarded one, is missing his pants. There’s a tiger in the bathroom and a baby in the closet. How they retrace their doings of the night before is intriguing in a narrative sense. But this is a comedy — or it’s meant to be — and as much as I would have loved for the sense of the sinister inherent in this concept to turn into something deeply, blackly funny. Lucas and Moore and director Todd Phillips go for the easy, cheap laughs, things that will shock a juvenile mind-set — a mother breastfeeding, a fat old man — instead of the things that would have unsettled a more mature one. Some are just plain disturbing without being funny: there are multiple intimations, for some reason that’s never clear, that Alan is a pedophile. Why would a doctor examine a patient while three total strangers are in the room? Why is a taser to the testicles “funny”? As if it knows, somewhere deep down, that it’s cheating, the movie has Stu insist, “You can’t just tase people because you think it’s funny,” but the movie does it anyway.