I think probably one of the funniest lines in all of Seinfeld was in the episode with Courtney Cox. -Jerry: "Honey, where's the can opener?" -Meryl(Courtney Cox): "It's in the first drawer." -Jerry: "I'm looking in the first drawer. It's not here." -Meryl: "Yes it is" -Jerry:"Hey...I'm not stupid. There's no can opener." -Meryl: "Did I say you were stupid?" -Jerry: "Well, wouldn't I have to be? You tell me there's a can opener in the drawer, I'm looking in the drawer, there's no can opener. What other conclusion could one reach?"
Some other ones are: -Kramer:"And you're an anti-dentite." -Jerry: "I am not an anti-dentite." -Kramer: "You're a RABID anti-dentite! Oh sure, it starts off with a few slurs. 'HEY! DENTIE!' Then you start thinking they should have their own schools." -Jerry: "They DO have their own schools." -Kramer: "YEAHEEYEAH!!"
-Kramer: "I'm like ice, buddy. When I don't like you, you got problems."
-Jerry(or Elaine?): "Why don't you just give him the jacket back?" -Kramer: "He'll have to kill me."
-Kramer: "Boy! I'm really surprised at you. You're the last person I'd expect to do something like this. Now George...I can see. Even Jerry. But not you, Elaine. I always kept you up here. They're over here. Now you're AAAAALLLLLLL the way down here."
-Kramer: "They got a great cafeteria downstairs. Hot food, sandwiches, a salad bar. It's like Sizzler opened up a hospital."
-George: "Jerry...kill me. Kill me now, I'm begging you. Just get it over with. Be a pal. Take the pillow, and put it over my face."
-George: "I WAS IN THE POOL!!"
-Newman: "Oh, how I've longed for this moment, Seinfeld. The moment that I had the proof I needed to haul you from your ??? lair and expose you to the light of justice as the monster that you are, a monster so vile..." -Other post office guy: "NEWMAN!!"
There's many others that I can't think of off hand