Amnesia might be the key to enjoying Todd Phillips's reprise of his 2009 hit comedy, since it follows by rote the formula set up in the original. Once again, the premise is like a Philip K. Dick story adapted by the Farrelly Brothers. Mousy Stu (Ed Helms) is the one getting married this time, and the wedding is taking place at fancy digs of his fiancée's family in Thailand. Against his better judgment, Stu has a beer on the beach with raffish Phil (Bradley Cooper), psychotic Alan (Zach Galifianakis), and the bride's teenage brother, Teddy (Mason Lee). The next thing you know, the three pals are waking up with no memory in a sleazy hotel room with a tattoo, a monkey, a severed finger, and Mr. Chow (Ken Leong) from the first movie. What they don't have is Teddy. After a barrage of uneven gross-out gags and some sour racial humor, they piece things together. Darker and more desperate than the previous go-round, this one might have done better just to sleep it off.