re: Is "The Hangover" the funniest movie in the last twenty years?

Saw The Hangover in the Theatre with no clue about it other than my buddy's recommendation. It was the hardest I've ever laughed in a theatre, including a lot of the movies listed here. I think a lot of its humor depends on the surprise element of the gag for max effect, so it's not as rewatchable as a lot of the others. But first viewing, in the theatre, it was insanely funny.

If the parameters of this discussion were "on first watch" it would be pretty high up there.