Dude, Where's My Car was an Oscar winner in comparion to The Hangover which was not only a ripoff, but a bad ripoff. More raunchy, less whitty. Nothing but corny raunchy jokes. I could see a bunch of geeks laughing saying "he just said penis hahahahaha" but that's about it lol. Dude where's my car at least had a fun plot the flowed and there was a real mystery with all the characters tying into together. The Hangover was just a bunch of garbage. Married a stripped with a baby and Mike Tyson ends up with them? Yeah, okay. The only funny creative parts (the 2-3 of them) were in the trailer.
Here's an example of the audience who enjoyed The Hangover:
:)
That said they are both are the bottom of the barrel of comedies, but The Hangover just wasn't even creative nor funny. Reminded me of Superbad only now I don't think so low of Superbad any more as at least its raunchy humor was clever.