Welcome to the Canteen!
"now listen up all you primitive screw heads..."
Welcome to the Canteen/asylum!! We may be weird, but we're lovable!!
The Evil Dead movies are some of the greatest movies ever made (I just wish I could get my girlfriend to appreciate them). The scene in Evil Dead 2 where his girlfriend's severed head is biting onto his hand so he's bashing it into the side of the house while running to the toolshed (for the vise - hehe) is one of the most insanely funny things I've ever seen. Also, if you haven't yet, check out Bruce Campbell in Bubba Hotep, another movie where he's got some great one liners.
Some other great cult movies are:
The Big Lebowski (FUNNY!!!)
Dog Soldiers (hard to find in the US, try Ebay -- it's worth it)
Fear and Loathing in Las Vegas (so completely over-the-top, even better when consuming copious amounts of your favorite beverage)
The Boondock Saints (violent though)
Starship Troopers (try not to take it seriously while watching, its better that way)
Thanks, OUSoonerFreeper, for adding your movie picks.