Dammit, sasshat, "Cool" was my pick.

*snaps fingers*

Boy, boy, crazy boy, get COOL, boy....

Pretty much every musical number from "The Sound of Music".

The dance scene in "The King and I". And also the dance scene in "Anna and The King" with Jodie Foster.
And pretty much everything from "Chicago".

la-dee-o-de-la-dee-o-de-lay-hee-hoo

Yes, Redvixen! Heck yes! I couldn't find any good youtube clips of the King and I.

Not a musical per se, but a big production number just the same: "We're Going To War", from Duck Soup.

I'd have to go with "With A Little Bit of Luck" from 1964's "My Fair Lady," or "If I Loved You" from 1956's Carousel.

Uncle Fucka is the greatest song in the Greatest Musical Ever Written: South Park: Bigger, Longer & Uncut.

[Terrance:] Shut your fucking face uncle fucka
You're a cock sucking ass licking uncle fucka
You're an uncle fucka, yes its true
Nobody fucks uncles quite like you

[Phillip:] Shut your fucking face uncle fucka
You're the one that fucked your uncle, uncle fucka
You dont eat or sleep or mow the lawn,
You just fuck your uncle all day long

[farting noises]
[Terrance:] Hmm!
[farting noises]
[laughing]
[farting noises]
[Some Guy:] What's going on here?
[farting noises]
[People:] OOOoooooooooooooh
Fucker fucker uncle fucka uncle fucka fucka fucka fucka
[T & P:] Shut your fucking face uncle fucka
[Terrance:] uncle fucka

[Terrance:] You're a boner biting bastard uncle fucka
[Phillip:] You're an uncle fucka I must say
[Terrance:] Well you fucked your uncle yesterday
[Everyone: (laughing)]
[People:] Uncle fucka... thats
[Everyone:] U-N-C-L-E fuck you Uncle
Fuckaaaaaa tonight...

[Phillip:] Suck my balls!

Ah, "Music Man". In high school, the drama department staged a production and got all the band members they could (including me) for an instrumentally unbalanced pit orchestra - more woodwinds than brass, far from 76 trombones. But as a bonus, a few of us musical geeks got to go up on stage to participate in the opening "Rock Island" number:

"Cash for the merchandise
Cash for the buttonhooks
Cash for the cotton goods
Cash for the hard goods
Cash for the fancy goods
Cash for the soft goods
Cash for the noggins
And the pickins
And the frickins
Cash for the hogshead cask
And demijohn
Cash for the crackers
And the pickles
And the flypaper
Look, whaddaya talk
Whaddaya talk, whaddaya talk
Whaddaya talk, whaddaya talk
Where do you get it?
Whaddaya talk?
You can talk, you can talk
You can bicker, you can talk
You can bicker, bicker, bicker
You can talk, you can talk
You can talk, talk, talk, talk,
Bicker, bicker, bicker
You can talk all you want
But it's different then it was
No it ain't, no it ain't
But you gotta know the territory..."

THAT was fun.

"I realize, of course, that it's no shame to be poor. But it's no great honor either! So what would have been so terrible if I had a small fortune?

"If I were a rich man -
Diddy diddy diddy diddy diddy dum
All day long I'd biddy biddy bum
If I were a wealthy man!"

The performance at the Palace Hotel Ballroom in The Blues Brothers

Or Ray Charles' performance in the same. Or Aretha's. Damnit, the whole movie.

Hell, the mall car chase.

I think it counts.

Seconding West Side Story. It just doesn't get any better.

"Snow" and "Sisters" from White Christmas are hard to beat for kitchsy perfection.

I will say that West Side Story is great if only because whenever I think about it, I instantly want to dance-fight.

"Look At Me, I'm Sandra Dee" - Grease
"Your Song" - Moulin Rouge
"And I Am Telling You" - Dreamgirls
"You're All The World To Me" - Royal Wedding (this is the song where Fred Astaire dances on the ceiling!)
"Cell Block Tango" - Chicago
"We Both Reached For The Gun" - Chicago
"Shoeless Joe From Hannibal MO" - Damn Yankees
" My Favorite Things" - The Sound of Music
"It's The Hard Knock Life" - Annie

And how about Oliver?

Hello Dolly

Portobello Road from Bedknobs and Broomsticks

Shuffle off to Buffalo from 42nd Street

Yankee Doodle Dandy starring James Cagney

Just these last two, and then bed, really. Oh heavens...Gene Kelly.

Oh, and how did I forget ...

"On My Own" and "I Dreamed a Dream" from Les Miserables.

Broadway Melody from Singin' in the Rain.

Just about everything from Sweet Charity.

And Some Enchanted Evening from South Pacific. "Once you have found her, never let her go." I always cry at that point.

i loved "uncle fucka" - in fact, it was that song that inspired me to make a beeline for the nearest record store and buy the soundtrack album immediately after seeing it. but after thinking about it, i think the funniest part of south park: bigger, longer, uncut was the closing credit ballad, "eyes of a child".

So, don't give up
Even when the road seems long
Just find that child inside you
(Yeah, you've gotta find you!)
Spread your wings and fly, to the brightest star
If you want, I can even get my friend Steve
To detail your car for like twenty bucks.

Through the eyes of a child
The world seems magical
There's a sparkle in their eyes,
They've yet to realise,
The darkness in their soul
The beauty of their smile
Adventurous and wild.
Sure, life is kinda gay,
But it doesn't seem that way,
Through the eyes of a child

the fact that they actually got arif mardin to produce the track and michael mcdonald to sing it has got to be the most subtle and subversive joke ever pulled on moviegoers.

Gotta go with Cabaret

I especially love the contrast between the opening scene and the corruption you can see at the very final scene.

I'm also a big fan of 'Tomorrow Belongs To Me,' but was reluctant to mention it, both because I've seen the movie a bunch of times but never seen the musical, and because, yeah, the other reason.

Funky Towel
Please be my bug

warning: don't click if you don't like cockroaches, dirty apartments, or singing cockroaches

I'm also a big fan of 'Tomorrow Belongs To Me,' but was reluctant to mention it, both because I've seen the movie a bunch of times but never seen the musical, and because, yeah, the other reason.

Ohh. yeah... that other reason's a damn big reason. But, speaking of the movie, well, it is a pretty impressive scene.