Right off the bat—poor dude is having his head forcefully flushed through his toilet at the behest of two random thugs...
Goon: WHERE'S THE MONEY, LEBOWSKI?! (shoves Dude's head in the toilet again) WHERE'S THE FUCKIN' MONEY, SHITHEEEAAD?! Dude: (legitimately confused) It's...it's... it's down there somewhere; let me take another look.
It very slowly dawns on them that they don't have the right place. "Isn't this guy supposed to be a millionaire, or something?"
Goon: (discovers Dude's bowling ball) ...What the fuck is this? Dude: Obviously, you're not a golfer. (Goon drops the bowling ball, cracking one of the tiles in the floor)
Inexplicably, the goons have switched outfits with each other when they return to The Dude's house.
"YOU SEE WHAT HAPPENS LARRY!? YOU SEE WHAT HAPPENS LARRY!? DO YOU SEE WHAT HAPPENS, LARRY, WHEN YOU FUCK A STRANGER IN THE ASS!?!"
Made even funnier in the TV edits, which turn the scene into a surreal Non Sequitur.
"DO YOU SEE WHAT HAPPENS WHEN YOU FIND A STRANGER IN THE ALPS?! DO YOU SEE WHAT HAPPENS LARRY?! THIS IS WHAT HAPPENS, LARRY, WHEN YOU FEED A SOLDIER SCRAMBLED EGGS!!"
The mere fact that Walter, a giant and alleged war veteran feels bested and "stonewalled" by Larry, a boy who doesn't even say a word.
(see Spit Take at the main page): "What is that, yoga?", "It increases the chances of conception" ...
The Dude barricades his door to prevent another breaking-and-entering. He forgot that the door opens the other way.
Even better later on, when the Dude trips over the barricade.
Walter "commends" Donny's remains to the Pacific Ocean. But the wind commends them all the way into the Dude's face.
The one and only line Walter delivers calmly: "And, I would like my undies back."
Walter enjoying his coffee... that is, making a scene at a family restaurant and being called out on it
Walter: Oh please, dear? For your information, the Supreme Court has roundly rejected prior restraint!!! Lady, I GOT BUDDIES WHO DIED FACE DOWN IN THE MUCK SO YOU AND I CAN ENJOY THIS FAMILY RESTAURANT (The Dude promptly leaves)
The Dude gets fed up with Walter and his bloody Simple Plan.
The police chief in Malibu (combined with Nausea Fuel, because he makes you so sick) throwing the coffee mug right in Dude's face after he replies "Sorry, I wasn't listening" to his long and cautionary "The Reason You Suck" Speech (in a way, the irritant indeference makes it look even funnier while almost justified, nevertheless). Enhanced by Dude's reaction ("Ow, fucking fascist!").
As The Dude is being hustled into Mr. Lebowski's limo, he yells out, "Hey, careful, man, there's a beverage here, man!"
"Also, Dude, Chinaman is not the preferred nomenclature. Asian-American, please."
The thug who defaces the rug pronouncing "Ever thus to deadbeats" in the process, as if making a political point a la "Syc Semper Tyrannis" in the assasinations of Gaius Julius Caesar and Abraham Lincoln.
The Dude, in good ol' Philip Marlowe mode, shades a notepad with a pencil to highlight the impression made on the next sheet of paper, only to discover Treehorn just drew a man with a big phallus.
Made doubly hilarious by the fact that the man is shaped like a giant phallus himself from torso upwards. In other words, a giant anthromorphic penis with a long erect penis of his own.
If you're mostly familiar with Philip Seymour Hoffman's serious roles, every one of his lines as The Comically SeriousLarge Ham Brandt becomes hysterical. Special mention goes to the limo scene:
Lebowski: They did not receive the money, you nitwit! They did not receive the money! Her life was in your hands!
Brandt:(adjusts glasses) This is our concern, Dude.
"But I hate the fucking Eagles, man..." Followed by the angry cab driver kicking the Dude out of his car.
This line by the Dude:
"Let me explain something to you. Um, I am not "Mr. Lebowski". You're Mr. Lebowski. I'm the Dude. So that's what you call me. You know, that or, uh, His Dudeness, or uh, Duder, or El Duderino if you're not into the whole brevity thing."