Airplane - “I picked the wrong day to give up amphetamines”
Happy Gilmore - Shooter McGavin kissing Happy’s Gran while she is wearing a Gene Simmons Mask. genius.
A funny thing Happened on the way to the forum.
but, my favourite has to be Spinal Tap. A musicians choice, pure and simple.
My Vote goes to Dr. Strangelove
“Gentleman you can’t fight in here this is a war room!!”
“Alright, I’ll get your money. But if you don’t get the president on the phone, you’re going to have to answer to the Coca Cola company!”
SAFETY LAST by Harold Lloyd.
SULLIVAN’S TRAVELS (anyone who liked O BROTHER WHERE ART THOU? needs to see this one.)
THE PRODUCERS (Broderick and Lane have nothing on Wilder and Mostel.)
LOST IN AMERICA by Albert Brooks.
I hated THE BIG LEBOWSKI the first time I saw it, but it’s grown on me during subsequent viewings. Rather like a fungus.
It’s not as laugh-out-loud funny as some, but GROUNDHOG DAY is one of the underrated gems of the last 10 years.
Spinal Tap
Waiting for Guffman (5 out of 5 stars)
Best in Show
I guess I have a thing for improv comedy.
Most of mine have been mentioned but I’d add some of the Ealing Comedies.
The Lady Killers http://us.imdb.com/Title?0048281 :- Alec Guinness is a genius.
The Lavender Hill Mob http://us.imdb.com/Title?0044829 :- Another classic with Mr. Guinness
Kind Hearts and Coronets http://us.imdb.com/Title?0041546 :- What can I say I love Alec Guinness(he play 8 characters in this) 
This is a true black comedy.
One more vote for “Monty Phyton and the Holy Grail”
Ni!
The blues brothers. A more perfect film was never made.
Holy Grail
Battlefied earth…WHat? It was supposed to be serious? Oh for the love of…
A movie on the list of almost every Texas Geologist I know (myself included)–and it’s good to see another one at the SDMB!
If you’re ever in the neighborhood, be sure and check out where DOM (actually, two "DOM"s are carved into the rock) is carved into the rock. The rock being some San Carlos Tuff, and the location being the top of the Big Hill along FM 170 overlooking the Rio Grande–right on the margin of the San Carlos caldera.
I agree with most of the stuff above, and I’m sure I’ll go it alone here, but one of the funniest movies I’ve seen recently is
[sub]What Women Want[/sub].
Mrs. WEW and I laughed so hard that we woke up the kids several times.
Tommy Boy
Airplane
Billy Madison
What can I say? I like 'em nice and low-brow.
I stil think “Tootsie” is one of the funniest…
Comedies seem harder to sort than other varieties – there’s too many movies with so many funny moments.
If I could only take one with me, it’d have to Airplane!. But I would like to say that Real Genius provided me with my best role model when I was growing up.
I’m adding the following ones I don’t think have been mentioned yet. I’m not saying they’re my favorites, just that they would be on my list.
In reverse alphabetical order :
Vacation
Real Life
The Philadelphia Story
The Naked Gun
East is East
A Christmas Story
Beverly Hills Cop
Best Parodies. I put these in separately because you need to be rather familiar with the originals to appreciate them (unlike, say, Airplane! [sup]*[/sup]). Again, in addition to any already mentioned:
**Robin Hood : Men in Tights **(Robin Hood films, most notably Kevin Costner’s)
Stiff Upper Lips (Merchant-Ivory (esp. the E.M. Forster ones), released at least ten years too late).
Top Secret!(Elvis films – while this one also came out long after the originals, it’s funny enough on its own rights to almost make into the upper list)
[sup]*[/sup] Of course knowing the originals makes it even funnier. I once saw a special on what was spoofed by it :
Airport & Airport '77 (plane disasters, one I think had the singing nun)
Zero Hour (another plane disaster, I think the sick girl, and the little boy asking questions in the cabin. I think he even had a dog. “Oh look, Scraps is a boy dog.”)
The TV series San Francisco International [sup] **[/sup], which starred Lloyd Bridges as air traffic director. (“Looks like I picked the wrong week to quit sniffing glue”).
[sup]**[/sup]The pilot of which was a MST3k episode, or so I’ve heard. Haven’t seen it yet.
Oooooh, lots of good choices, but I’m going to name a film that nobody has mentioned yet!
BRAIN DONORS!
For those who don’t know (and that seems to be everybody in this thread), it was a modern-day remake of the Marx Brothers’ movie A Night At The Opera. It tries to recapture the manic Marx feel of the original, and succeeds in spades – there’s nonstop gag action, highbrow subtle wordplay, outrageous situations, lowbrow slapstick, men in drag, beautiful women, and a manic ending that leaves you breathless.
If you like the Marx Brothers, or you just enjoy laughing so hard until your sides ache, this is the movie to see. Pity it bombed at the box office, as there’s no chance of any sort of sequels, and nobody else I know has ever heard of it…
Three Amigos!
Three-way tie:
Life of Brian
Airplane
South Park: Bigger, Longer & Uncut
What, no one mentioned Forbidden Zone?
That’s some funny stuff, boy…
The best comedy, obviously, is The Producers.
But here’s some of the best, lesser-known comedies:
Drunken Master
Jackie Chan
The Kid Brother
Harold Loyd
To Be Or Not To Be
Ernest Lubitsch
(Note: I’ve never seen the Mel Brooks version, but it would be hard to top the original. Who knew Jack Benny was actually funny?)
Peewee’s Big Adventure
Tim Burton
(This isn’t so lesser-known, but it’s one of my faves)
Black Wednesday (or The Sin Of Harold Diddlebock)
Preston Sturges
Starring Harold Loyd
(Or ‘Christmas In July’, ‘The Lady Eve’… just about anything by Preston Sturges)
The Bank Dick
It’s A Gift
[Never Give A Sucker An Even Break*
Christ, is W.C. Fields funny!
Pee Wee’s Big Adventure has always cracked me up. “Is this something you can share with the rest of us, Amazing Larry?!?!?!” Too bad the sequel sucked.
Bananas. An almost forgotten Woody Allen movie based on a short story he wrote, it has always been my favorite of his. I love the Howard Cosell parts, and the trial scene makes you realize the Airplane! style of comedy did not originate with the ZAZ boys. And what 13 year old boy would not love the snakebite gag when he first sees it?
“I’m All Right, Jack” and “Being There,” two movies starring Peter Sellers. That man was a genius.
Funniest films: Bowfinger was good, Obviously MP & the Holy Grail and I enjoyed Galaxy Quest a lot. Ooop, trekiness showed there. Retract! Retract!
Peter Sellers was a drinking buddy of my Uncle Ronnie - a nomadic alcoholic with many children. They’d have competitions and drinking games. That is until Peter Sellers passed away… Ronnie disappeared too, oddly enough. (NOT BS BTW)