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

The Hangover would get consideration from me because it was a unique idea and really funny.

If I had to pick one that stands out over the rest of those mentioned, I'd go with Old School. I was in my mid-20's when it was released so I could identify with much of it. Frank the Tank had moments of being a serious character and also the extreme. Most circles of friends also have a character like Vince Vaughn's that keeps pushing the envelope. The cameo by Snoop a Loop is the tie-breaker for me in saying it's my favorite recent comedy.