Oh, so many choices. At this particular moment (subject to frequent change), I’m going to pick this one, from The Cartridge Family.
Gun Shop Owner: Sorry, the law requires a five-day waiting period. We’ve got to run a background check.
Homer: Five days? But I’m mad now! [growls in a low, crazy voice] I’d kill you if I had my gun!
Gun Shop Owner: Yeah, well, you don’t.
It’s making me laugh just thinking about it.
From the episode where Lisa has a crush on Nelson.
Lisa gives a note to Milhouse, who in turn must pass it up to Nelson in class. He opens it up and its says “Someone likes you.” Nelson looks back and sees Milhouse waving at him. The scene then cuts to Milhouse being rushed into an ambulance on a stretcher.
Lisa: Milhouse! I’m so sorry!
Paramedic: He can’t hear you…
I’m laughing now as I type this.
Homer’s various prayers are always hilarious. We’ve already had the “Superman” one, but the others…
HOMER: “Dear God… the gods have been good to me…”
HOMER: “Oh God, if you are God…”
MARGE: “Homer, that’s a waffle that’s been stuck to the ceiling.”
Or what about the episode where Grandpa is in charge of taking care of Bart and Lisa, and they trash the house? To clean everything up, they shove it all under the carpet, resulting in a pulsating, unstable mass that shifts as they walk across it. One of the noises is, “Hey, watch it!”
Or how 'bout…
GRANDPA: “Hey, your lamp’s running away!”
BART: “What? That’s my dog, man!”
GRANDPA: “Goodbye, lamp!”
The very first episode I ever saw was the one where the Simpsons all go to the clinic to get some “family therapy” and they’re attached to machines that allow them to administer electric shocks to each other. I laughed so hard that I almost threw up.
The Itchy and Scratchy episode set in a mall is the best.
As the cat’s riding up an escalator, the mouse nails his foot down. Upon arriving at the top, he’s pulled into the teeth, leaving his fur behind. Mouse sells fur to a furrier, who in turn sells the pelt to a woman. When she walks out of the store, there is a skinless cat, in all of his muscular glory, glaring at her.
The sight of those exposed muscles and his peeved look just about caused me to wet my pants.
It was one of the very first episodes, back in '89 or so. Homer is at the RV dealership; after the credit check sets off a siren, the salesman shows him a crappy, beat-up old RV that’s barely holding together. Homer protests that he liked the nicer ones.
Salesman: “Mr. Simpson, this is the finest RV you will ever own. And I don’t mean that in a good way; I mean this is it for you.”
From “Last Exit to Springfield”:
Scene: the workers at the Springfield Nuclear Power Plant are on strike, and are demonstrating outside. Mr. Burns orders Smithers to bring him some strike-breakers, like they had in the thirties. Smithers brings in Grandpa and a couple of his pals.
GRANDPA: We can’t bust heads like we used to, but we have our ways. One trick is to tell 'em stories that don’t go anywhere…like the time I took the ferry over to Shelbyville. I needed a new heel for my shoe, so I decided to go to Morganville, which is what they called Shelbyville in those days. So I tied an onion to my belt, which was the style at the time. Now, to take the ferry cost a nickel, and in those days, nickels had pictures of bumblebees on 'em. “Gimme five bees for a quarter,” you’d say.
Now where were we? Oh, yeah. The important thing was that I had an onion on my belt, which was the style at the time. They didn’t have white onions because of the war. The only thing you could get was those big yellow ones…
You forgot the BEST part! After glaring at her, Scratchy takes his skin back and drapes it around his neck… as he’s walking outside, he’s beaten by some anti-fur activists! 
My personal favourite has always been when Bart is building a go-kart, and Homer would like to help. However, he thinks that offering to help will mean that Bart will automatically say no, and has a conversation with his brain:
Homer reads, in “Fatherhood” by Bill Cosby, that children will always do the opposite of what you tell them to do.
Homer: Don’t you get it? You’ve got to use reverse psychology!
“That sounds too hard.”
Okay, don’t use reverse psychology.
Homer changes his mind: “All right, I will!”
My favourite is non-verbal, it’s in the Cape Fear spoof where Sideshow Bob keeps stepping on the rakes. That makes me laugh like a drain everytime I see it.
I also liked the episode where they said “wankers”.
In the episode where Homer has a sleeping disorder (apneu?) Marge is driving the kids to school.
She hasn’t had any sleep due to Homer’s constant snoring.
So she starts to fall asleep behind the wheel.
Her head slouches forward and hits the horn.
With that she jumps back to live, shouts “I’ll get it” and jumps out of the driving car.
After sliding down side of cooling tower, Homer smashes through the window into his car and drives madly away singing,
Better yet (damn, I have so many favourite moments),
We laughed, we cried!!
I enjoyed the bit in Brother From the Same Planet where Homer and Bart engage in a “Who’s Afraid of Virginia Woolf?” dialoge, and Homer sounds like Richard Burton.
Homer (sitting on the stairs in the semi-dark): Hello son. Where were you?
Bart: I was out playing with Milhouse.
Homer: No you weren’t! You were out galivating with that floozy of a bigger brother. Look at me when I’m talking. Look at me!
Bart: Dad, you’re taking this too hard. It just sort of happened.
Homer: Oh, and how do you want me to take it? Go ahead Bart, have your fun? Sorry, I can’t do it.
Bart: Oh yeah? What are you going to do about it?
Homer (pours wine): Oh, you’ll see.
In the “Song & Dance” catagory, the nominees are…
See My Vest.
Maison Derriere.
Monorail.
I like any of the “dirty” jokes that they sneak in.
Krusty See ‘n’ Say: “S is for shiksa! S…H…I…um…I think there’s a T in there…”
Or the Springfield Heights Institute of Technology (S.H.I.T.)
Or the “Sneed’s Feeds and Seeds (Formerly Chuck’s)” sign.
For that matter, most of their business name signs are killer. Like the gun store, “Blood Bath & Beyond”, or the musical instrument shop, “King Toot’s”, or the toy store in Chinatown, “Toys ‘L’ Us”.
In the episode where Homer climbs the Murderhorn, he tells the family that he’s only eating food in bar form now, so he pours 5 pounds of spaghetti into a machine that makes it into a small bar. He takes a bite, looks thoughtful, then picks up the phone and says, “Hospital, please.”
From $pringfield: Marge is at the casino all the time, there aren’t any dishes, no one has been grocery shopping, and Lisa is concerned about what they’re going to eat for breakfast. Homer tells her to be creative and takes out a miniature pie crust and fills it with cloves and Tom Collins mix. He then takes a bite, gets a horrified look on his face, and agrees that they must get Marge back.
When Homer was attracted to female co-worker Mindy Simmons (voice of Michelle Pheiffer), he attempts to get his mind off of her when he sees her in an elevator by “think[ing] unsexy thoughts.” The result: Barney in a bikini, drunkenly humming the theme from I Dream of Jeannie.
And here’s a two-for-one: “Stoner’s Pot Palace” (a Crate & Barrell-type place)
Otto: Man, that is FRAGRANT false advertising!
I don’t get this one. Help please.
:slaps owlstretchingtime with a cold, wet trout: