After Jerry accidentally erases the bootleg video, and Kramer tells him that the gun-toting guy is on his way up:
Kramer: “I’m sure he’ll understand”.
Jerry: “People with guns don’t ‘understand’! That’s why they GET GUNS!”
A lot of it is in the delivery. A neurotic Manhattanite who’s probably never seen a gun except on a cop.
Kramer, trying to convince Jerry to make a thank-you call:
“Aren’t you a part of society? Because if you don’t want to be a part of society, Jerry, why don’t you just get in your car and move to the East Side!”
Believe it or not, George isn’t at home
So leave a message at the beep.
I must be out, or I’d pick up the phone.
Where could I be?
Believe it or not, I’m not home.
Serenity now, insanity later.
I could drop you like a bag of dirt.
I loved the two-parter where Puddy gets everybody to facepaint for a New Jersey Devils game, and they terrify a priest.
Elaine: YOUR BALD!
George: "I WAS bald!
His bald what?!? 
GEORGE: I can’t believe it. Look, that’s Jerry Seinfeld.
DEENA: Who?
GEORGE: Jerry Seinfeld. My best friend. He can explain all of this. (calls to
Jerry) Jerry.
Jerry hears his name called and turns his head, but all he can see are blurry
colored shapes.
GEORGE: Jerry! Over here Jerry. It’s me!
The car pulls away, leaving George calling after it.
GEORGE: Jerry, where y’going? It’s… what’re…
DEENA: (doubtful) That was your best friend?
GEORGE: Yeah, yeah, but he doesn’t wear glasses.
DEENA: That man was wearing glasses.
GEORGE: I know. Don’t you see. (emphatic) He was doing it to fool Lloyd Braun!
My favourite scene was Crazy Joe Davola, in his clown suit, beating up the punks in Central Park.
I like the one that comes later, where Kramer isn’t quite sure who he’s talking to:
CRAZY JOE: (In his clown suit) Do you like clowns?
KRAMER: (Freaking out) Uhhh … yeah…?
Yes, absolutely! Season 4, with Crazy Joe and Dr Reston, is my favourite, although there is just so much in the entire show.
Never a fan, but I thought an episode where the incident (from faulty memory) of a baseball player getting spit on was compared to the assassination of JFK was pretty clever.
It was Kramer who got spat on, and that scene was a parody of the courtroom reenactment of the assassination in Oliver Stone’s JFK.
Wayne “Newman!” Knight was in both, so he must have had a strong feeling of deja vu.
I wonder why I thought a baseball player was involved?
He was, but not in the reenactment. He was Jerry’s new man-buddy Keith Hernandez, and the spitting incident occurred after one of his games as Kramer and Newman were leaving the stadium.
IIRC Kramer thought Hernandez had spit on them after they called him “pretty boy” but it turned out to be Roger McDowell (“the second spitter”) hiding behind a bush.
“That was one magic loogy.”
Frank Costanza cracking an egg into a pan: "I’m back, baby!"
Peterman: “My neck is one gargantuan monkey fist.”
“Tippy-toe! Tippy-toe!”