Lock, Stock and Two Smoking Barrels
Snatch
The Fifth Element (Sc-Fi/action/comedy, but still very funny)
Clerks/Mallrats/Chasing Amy/Dogma/Jay and Silent Bob Strike Back/Clerks 2/Clerks Animated
UHF
Army of Darkness

Army of Darkness
Kung Pow: Enter the Fist
Dumb & Dumber (quite possibly the funniest, most perfect movie ever)
Half Baked
Blazing Saddles
The Boondock Saints
Napoleon Dynamite (seriously, the first time you watch it you're like "....ok" then you watch it again. then again) [and again]

then there's Wes Anderson films:

The Royal Tenenbaums
Bottle Rocket
The Life Aquatic

...I havent seen Rushmore yet but I usually put on one of those 3 at least once a week even if it's just background noise because it makes me happy knowing it's playing. The soundtracks for those films are amazing as well.

I really liked Raising Arizona.

Also, Napoleon Dynamite is only funny to people who haven't met any real hopeless, spiritless husks inescapably mired in misery. Or they don't get it. Or they're sociopaths.

Dodgeball wasn't bad.

Get all four seasons of the british show Coupling. Its hilarious.

Clerks all the way, especially if you work/have worked in customer service. Best Kevin Smith movie ever.

The Big Lebowski.

Will Ferrill's worst movie... Watch ELF instead

Anchorman

Holy god that film is hilarious.

Blazing Saddles
Withnail & I

This Is Spinal Tap

Can't believe that nobody has mentioned this film yet, its ****ing brilliant, well, thats four of my favourite comedies.

<spe> people who don't like anchorman love hitler

The Austin Powers movies, especially the first two. A lot of people don't like them, but I find them hilarious.

Also, House of the Dead, I haven't even seen it but with quotes like these it seems brilliant.

Yup, last year my housemates were always stealing my Coupling DVDs

Airplane!

Ok, i just want to set a few people straight on this movie. Everyone's going around saying that those who don't find it funny is because they actually are like napolean, or like Ictus here, that you have to think of Napolean's situation as impossible to find it funny. i jsut wanted to stick in here that for a few years, i frelling was napolean. Well, obviously, not the whole situation, but the friends, the girls looking at me like i was something they stepped in, the feeling every day of '**** it, why do i bother? no one cares'. For about two years, i was exactly like that. And i found the movie incredibly hilarious. so did all my friends, some of whom were also in this situation. I think, if you were like that, and find it horrible, or whatnot, to loosen up. If you can't laugh at yourself, you're lost. I think the point of the movie was to apply to everyone, to poke fun at the little insecure dork in everyone, and say 'Hey, you never know, man. You never know."

[edit] might as well put my two cents in for the comedy movies, as well. I didn't read all this, so i don't care if they were asid before:

Dodgeball
Shaun of the Dead
Evternal Sunshine of the Spotless Mind (depedns on the situation. Its very funny, but is witty, dry humor)
Hitchhiker's guide to the Galaxy
Life Aquatic with Steve Zissou (The humor in this is so dry it makes eternal sunshine look sopping wet. But if you manage to follow it and like the artisitc style, its a hilarious movie)

Anchorman: The Legend of Ron Burgundy
Will Ferrell is a sexist anchorman in San Diego. He and his buddies have a bad reaction when a strong willed woman named Veronica Corningstone joins the station. The film details his meteoric fall from grace and embarassing struggle to rise again, complete with Jack Black stating how he rolls and the best fight scene between Tim Robbins, Vince Vaughn, Ben Stiller, Will Ferrell, and Steve Carell EVER filmed.

The Big Lebowski
Jeff "The Dude" Lebowski (Jeff Bridges), formerly of the Seattle Seven, the Port Huron Statement (The original, not the compromised second draft) and the Metallica "Speed of Sound" tour, is living in sunny Los Angelos. One day, some thugs from a guy named Jackie Treehorn bust into his house, ruin his milk, crack his bathroom floor, insult him, and, here's the clencher, they piss on his ****ing rug. That was a valuable rug. It really tied the room together. The Dude's reactionary vietnam vet friend Walter (John Goodman) advises that the Dude Lebowski seek out the true target of the carpet pissing, the millionaire Geoffery Lebowski. This is where the Dude's life falls apart. The Dude never wanted any trouble. The Dude never wanted to get involved in a kidnapping struggle or a vicious rumble in the parking lot of his favorite bowling alley. All the dude ever wanted was his rug back.
**** it dude, let's go bowling.

Kung Pow: Enter the Fist!
Meet Chosen One (Steve Oedekerk's head pasted on Hui Lou Chen's body), the warrior who will do some crazy stuff with a weird thing on his tongue. It's not a porn movie. He must fight the evil "Betty" witht he help of various poorly dubbed friends. He must destroy the little pyramid cap thingies of evil. He must not look like a total dork while trying to grab Betty's chest. He must get a lot of nuts. He must beware the guardian in the pasture. He must...
You know what? this movie's really silly and stupid. Seriously, it's a laugh and a half.

This is Spinal Tap
Four... well, three musicians from England, plus a drummer living on borrowed time, venture into the wilderness of America in order to keep this crazy tradition going a little longer. They've been playing since the early 60's (when the lead singer still had blue eyes) and it's now the mid 80's, and they're blowing all the other hair bands out of the water... well, not really. Will they succeed in their "Smell the Glove" tour? Will they stick together through herpes, 18" tall stonehenges, and cancellation after cancellation? Can they find their way to the stage, or will they forever be trapped somewhere far behind the curtain screaming "Hello Detroit!" How much blacker can it get? The answer is none. Not, uh, none blacker.

The Life Aquatic
Half Jacques Cousteau, half washed up Steve Irwin, half Lost in Translation, half Pirates of the Carribean. That's two full movies of weirdness. Seriously.
Steve Zissou is washed up, lame, and rediculous. Nobody really believes that his friend Estaban was eaten by the mysterious "Jaguar Shark". Now there's this guy named Ned Plimpton (played by the lovely and talented Owen Wilson) who says he might be Steve's son. There's a journalist by the name of Jane Richardson chronicaling his latest journey (the pregnant and talented Cate Blanchette). There's his estranged wife, our for his balls (the haughty and talented Anjelica Houston). A whiny first mate (the aging and talented Willem Defoe) and a bond company stooge (the portly and talented Bud Cort) round out his crew, as he faces off agains the dastardly Alistair Hennessey (the gaunt and talented Jeff Goldblum), his wife's ex-husband.
This is an adventure.

Bandits
Joe Blake and Terry Collins are the sleepover bandits, taking bank managers hostage in the evening then robbing their banks the next morning. It's a good racket until Terry gets involved with a woman as mentally and emotionally ****ed up as him, Kate Wheeler. Joe and Kate immediately fall for one another, and a few heists later, get seperated by circumstances, strandign Terry with Kate, who also hit it off. The wacky stuntman/frontman Harvey Pollard, their getaway driver, is constantly distracted by the spectre of a pink-booted blonde hitchiker, and the melodramatic Darren Head, host of Criminals at large, is desperately on their case. Word of advice to all bank robbers:
If you ever think you're going to be apprehended, if this is your "last big job", don't robt a bank in downtown Los Angelos. If you do, don't show the tellers your guns, just do it the old fashioned way. If you do, make sure the bank's not called "The Alamo". Bad Karma.

-Teh end.

HURCULES RETURNS. i know my movies and this one is the funniest one ive ever seen. also you might want to try lone wolf mquade. only watch that one with your firends though. its super funny.