Here's the thing. The first Hangover was funny because everybody was trying to remember what happened.
The second Hangover needs you to remember just enough about the first Hangover as you watch everybody try to recollect what happened all over again, somewhere else.
It's another movie driven by amnesia, but one that also comes with a sense of deja vu.
And like the outlandish first, it sure is memorable - mainly for showing stuff you wish you could forget, though the most cringeworthy comes in the gag photo gallery in the final credits.
So, yes, The Hangover II is quite a hoot. Not as manic and full of surprises as the Las Vegas original which became a runaway hit and one of the highest grossing gross comedies of all time. But with Bangkok upping the sin city stakes, and giving this its own steamy, seamy sense of the ridiculous, part II keeps up a steady chuckle count throughout.
It helps that the core trio of party boy Phil (Bradley Cooper), uptight Stu (Ed Helms), and the juvenile Alan (a scene-stealing Zach Galifianakis) remain quite the triple act. Watching them mutually infuriate each other - as only mates can - as they try to figure out their latest pre-nuptial mess is half the fun.
This time it's Stu getting hitched. Two years after the Vegas shenanigans, he's set to wed his Thai girlfriend at a resort in her homeland. Against his better judgment, Stu brings his mates.
Mysteriously, two nights before the big day, they wake up in a seedy Bangkok hotel. They've gained a monkey, and another posse member - the unhinged gangsta Mr Chow (Ken Jeong) from the first flick.
But they've lost Alan's hair and Stu's teenage brother-in-law-to-be Teddy (Mason Lee, the son of Ang Lee), as well as any memory of how they got there.
Helpfully, though the kid has left one of his fingers behind ...
And watching them put the jigsaw back together to find Teddy in time to make the ceremony does just what the first movie did. And considering the place they're in, there's only a few surprises about their night-before adventures, including a somewhat inevitable Crying Game moment.
There's also Paul Giamatti as a crime boss, some trigger-happy Russian gangsters and yes Stu's troublesome Tyson tattoo and Alan's meditation-induced flashback, in which his inner child - who is never far from the surface at the best of times - emerges with those of his pals in a piece of trippy silliness.
It's an unusually well-appointed movie for a comedy, with atmospheric cinematography, a decent car chase and a soundtrack which neatly pits Kanye against Johnny Cash, uses Billy Joel tunes as a running gag and has good fun with the unavoidable One Night in Bangkok.
No, the film itself isn't exactly singing a different tune. But its unflinching take on men behaving badly and its sense of mischief remains infectious. Though you may not like yourself in the morning for what you laughed at the night before.
Cast: Ed Helms, Bradley Cooper, Zach Galifianakis
Director: Todd Phillips
Rating: R16 (offensive language, drug use & sexual content)
Running time: 102 mins
Verdict: Brash Bangkok sequel to stag do comedy hit.