Go rent the first movie and pretend they are in Bangkok.
Here is what else is a little different (SPOILER ALERT - so don't blame me if you keep reading).
Stu (Ed Helms) sleeps with a she male, the ever revolving rumors of celebrity cameos (first it was Mel Gibson and then Liam Neeson) turns out to be Mike Tyson & Paul Giamatti, Alan (Zach Galifianakis) shaves his head, Phil (Bradley Cooper) gets shot, there is a drug monkey which smokes. Mr. Chow (Ken Jeong) and Doug (Justin Bartha) get about the same amount of screen time as they got in the first one.
See, I told you to stay home and just see the first one again.