If you're a fan of the Cheech & Chong pot-filled stoner humor genre, you're gonna love this 2004 comedy. The scene where two girls sitting in bathroom stalls play "Battleshits" while the heroes hide between them silently suffering the sounds and smells is one of the funniest you'll see in a movie.
Harold is a twenty-something investment banker, very serious and nerdy. His friend Kumar is a brilliant but lazy pre-med student, and nothing in his life is taken seriously. Their common bond is a love of pot. After smoking one night, they decide to find a White Castle to get some sliders.
Needless to say, the trip doesn't go smoothly, as they confronted by skinheads, cops, a tow truck driver whose wife wants a three-way, the above-mentioned battleshitters, and a lot more crazy events too numerious to mention. Every possible ethnic sterotype is exploited in this movie, and it's damned funny.
I think this one would be funny even if you saw it straight, not that I'm recommending that. One way or the other, see it.