Another classic scene in an otherwise bleh movie: Skin Deep, when the two men chase each other around the bedroom, each wearing a glow-in-the-dark condom…in the dark. 
The one-liner scene from Roxanne.
And on and on.
Oddly, this was the first scene that popped into my head when I saw the thread title, and I barely even remember watching Roxanne. I just know the scene from various quotations on the net, and imagining Steve Martin going through it is enough to set me off.
Another Clue fan here, though I can’t think of any specific scene.
Another underrated movie is Undercover Blues. Just about any scene with Morty (“EL MUERTE!”) is an absolute riot.
I’m going to throw in Evil Dead 2, particularly, the sceen where the old lady zombie is trying to escape from the basement. They can’t seem to close the basement hatch so one of the guys does the funniest thing I’ve seen in a horror movie in a long time…full swinging football punt to the face! Wwwapppooowwww!!!
I’m laughing right now typing about it!
I can’t for the life of me recall the film , but it was one of those middling Eddie Murphy comedies where he played multiple roles - Eddie is renting a New York aprtament, and there’s the chalk outline of a body on the floor, and a blind man’s cane… and a seeing eye dog. And the landlord says real slow and sad “Damn shame what they did to that dog…”
Favourite not meant to be funny scene - when George C Scott trips over his own feet in Dr Strangelove.
mm
that could be Coming To America
The first few minutes of Not Another Teen Movie.
The mime scene in The Aristocrats. I swear, my face was aching from laughing.
There are two:
In Austin Powers II: the Spy who Shagged Me when Dr. Evil and Scott go on Jerry Springer in the opening scene and Dr. Evil is running around with the Klansman’s hood yelling “I got the hood! I got the hood!”
and
In Spinal Tap when the midget is dancing around the 18 inch stonehenge and is, of course, MUCH taller than it.
in Airplane! Lloyd Bridges and Robert Stack are in the control tower shouting orders at Robert Hayes. Stack shouts several instructions into the radio, the last one being "Push a button!!!"
Not to mention the incredible bumbling act at the end where he’s talking to the girls as he’s knocking stuff off the table and catching it and putting it back and knocking it off, and she’s trying so desperately not to absolutely shit while he’s doing it.
And I liked one line in Bruce Almighty, where they are up on the mountain and God tells Bruce he’s dead. From IMDB.com:
Bruce: [being overwhelmed with hearing prayers] Give me a break!
[Bruce is instantly transported to meet with God]
God: Really something, isn’t it?
Bruce: Is this heaven?
God: No, this is Mount Everest. You should flip on the Discovery Channel from time to time. But I guess you can’t now, being dead and all.
[pause]
Bruce: I’m dead?
God: Naw, I’m just messing with ya.
Bruce: That’s not funny, Man! That is not funny.
Morgan Freeman’s delivery of the “messing with ya” line is absolutely classic. I’m glad I wasn’t eating any popcorn when he said; I’d have probably hit the screen spitting it.
(long time lurker, first time poster… )
I’ll see you’re Shaun of the Dead and raise you the dance scene from Dead and Breakfast …
“We’re comin’ to getcha, we’re comin’ to getcha”
One of my favorites, too.
And I don’t think that ANYTHING tops the end of the movie, where Tim Curry is recapping the events of the evening (step by step).
More love for Clue here.
I just loved from The Gods Must Be Crazy the whole bit about the Landrover being called ‘The Antichrist.’ And then went on to prove it.
A scene that I think I was the only person in the whole theatre to bust a guy laughing at was at the climax to Naked Gun 2 1/2 when the crowd is panicking after the word that there is an Atomic Bomb in the area, and someone runs up to the camera shouting, “It’s a cookbook! It’s a cookbook!” (Of course while holding a folio-sized book titled: To Serve Man.
Many of my favorites have been mentioned, but I’ll add these:
Rat Race - The cow hitting the windshield of the bus. That one had me on the floor.
South Park: Bigger, Longer and Uncut - Stan finds the clitoris. Totally unexpected.
Top Secret - “What fake dog poo?”
Top Secret’s Underwater barfight. Completely out of left field.
Young Frankenstien
The entire ‘Blind man’ scene.
Gene Wilders’ introductory lecture rant culminating with a scalpel to the leg.
“Give him a SEDAGIVE?!”
"I need to see your license and registration, meow!
Foul Play – the chase scene to the opera house. Particularly the limo ride: “Kojak, bang, bang?”
Another great San Francisco trip across town is in Nine Months. Rolling upt to the ER with a carload of patients, and sorting them out to the staff.
How can I forget Four Weddings and a Funeral. Funniest scene? I don’t know. Maybe the rings at the first wedding.
"A riot - iss an ugly ting. Und vunce you get vun shtarted, zere is little shance of ending it, short of bloodshed.
Und so - before ve go arount gulling people -
Ve had better make DAMN sure of our evidence."
And then the dart scene. Oh gad, I am giggling just thinking about it.
Regards,
Shodan
“Roll, roll, roll in the hay”
“I swear to God: I’m going to pistol whip the next guy who says ‘Shenanigans’.”
“Hey Farva, what’s the name of that restaurant you like with all the goofy shit on the wall and the mozzarella sticks?”
“You mean Shenanigans?”
“Oooooohhh! [holding up the butt of his pistol]”
Gets me every time.