A seemingly interminable slog through the Bangkok underworld, where a familiar scenario plays itself out to the point of exhaustion for three wedding-bound wrecks – searching once more for a misplaced buddy – arrives by way of The Hangover Part II. Whether nostalgia in this case breeds delight or contempt depends on which aspects of the original Hangover (2009) you remember most fondly.

One quality shared by most of director Todd Phillips' comedies – his credits include Old School (2003) and last year’s Due Date – is a desire to shock by any means necessary. Part II excels in this but overplays its hand. At some point it manages to make full-frontal male (and even she-male) nudity seem less naughty than tedious, a tired substitute for actual comedy.

When fully clothed, the members of the original “Wolfpack” – suave instigator Phil (Bradley Cooper); nerdy dentist Stu (Ed Helms); and wide-eyed man-child Alan (Zach Galifianakis) – having survived their more memorable lost weekend in Vegas, stumble into an improbable caper involving a drug-dealing monkey, killer crime bosses and old friend Mr. Chow (Ken Jeong).

The action is fast and deafening, and indeed Part II is more violent than its predecessor. (At one point, the boys, seeking answers in a monastery about their ill-fated night before, are paddled by monks for disturbing the silence. The punishment fits.)

What’s missing from this demented travelogue is a sense of humor grounded in something more substantial than scatology and gratuitous mayhem. Phillips and co-writers Craig Mazin and Scot Armstrong place their befuddled party boys in scenarios absurd enough to guarantee a few laughs, and occasionally they do.

But on some level all their frustratingly slow-footed detective work, and all the wild-and-crazy encounters it yields, actually distract from the best thing about the movie not named Mike Tyson. (In a brief cameo, the champ scores another knockout.) That would be Phil, Stu and Alan, three stooges whose stark differences suggest an uneasy partnership and the kind of off-kilter exchanges their harried conversations tend to produce.

We could watch them eat lunch together – and at one point, early on, we do – and comedy might seem unavoidable. Yet this sequel, which amplifies every quality of the original except its humor, gives them more trouble than they or we need. The effect is that of a real-life hangover – a headache and a nagging sense of regret.