During Spring Break we watched The Hangover (2009,R).  From ScreenIt!:

When a groom-to-be ends up missing after a wild night in Vegas, his two best friends and future brother-in-law try to find him by piecing together what occurred since none of them can remember anything.

It's clever and funny and Zach Galifianakis steals scene after scene.

I give it 4 out of 5.