Burns: ... Homer Simpson.
Smithers: Homer Simson? He's one of your boobs from sector semen, I mean sector 7-G sir!
Lisa and the woman who created Malibu Stacy:
Lisa: so they kicked you out of the company because you didn't agree with their views?
Woman: Yes. Well... that and I was funneling profits for personal gain.
Lisa: Dad, I wouldn't sell Stampy (the elephant) to that man. I think he's an ivory dealer. His boots are ivory, his hat is ivory, and I'm pretty sure that cheque is ivory (flicks the cheque and it makes a hollow sound).
Homer: Lisa, an ivory dealer is less likely to kill Stampy than someone whose ivory supplies are low!
Millhouse showing Bart his new game Bonestorm II (or Bloodstorm II, whatever the name may be).
Millhouse: "This game is amazing, and all I've done is enter my name - Thrillhouse!" Written on the tv-screen in all capital letters, shortened to 8 characters: "THRILLHO"
Bart: Homer, your half-assed underparenting was a lot better than your half-assed overparenting.
Homer: But I was using my whole ass!
Homer and Marge are up on the makeout hill by the big Springfiled Sign as teenagers.
Homer (excited): Oh look marge, a new weather station. I'll bash it good!
-bashes the radio transmitter with a metal object
Homer (completely changes tone, drops the metal object then approaches Marge): You got real pretty hair.
Apu: These hot dogs are only for show, they're over 3 years old. Well, there's one bozo who comes here and ...
Homer (muffled): Hm, but I buy those (trails off)
Doctor Nick goes to hospital door and opens it slightly. A flood of reporters are seen, one voice rises above the rest: "Doctor Nick, where did you hide the bodies?"
Doctor Nick: "It's such a lovely day, I think I'll go out the window" (jumps out the window).
Doctor Nick: Well if it isn't my old friend Mr. McGregg. With a leg for an arm and and arm for a leg. (you have to see it to know what I'm talking about).
Ralph: It tastes like... burning! (posted earlier - it's a good one!)
Homer (looking at his house as it's in flames and the fire jumps over to Flanders' house): Look at that, Flanders is the most religious person I know and god didn't save his house.
-A holy cloud appears and puts out the flames.
Lisa falls into the "water" which is probably beer at Duff gardens while being accompanied by Aunt Patty.
Man to Aunt Patty after she falls into the "water" at Duff Gardens: "Give her these (hands her pills), and these (more pills), and these (even more pills).
Aunt Patty: "Thank you Doctor"
Man: "Oh I'm not a doctor!"
Kang and Kodos the aliens infest Bob Dole and Bill Clinton's bodies and are seen together.
PR-Guy to Clinton: "Mr Clinton, everyone wants to know why you and your opponent (for the upcoming election) are constantly holding hands.
Clinton (totally Kang the alien's voice): "We're simply exchanging long protein strands. If you can think of a better way, then I'd like to hear it!"
Basically anything Ralph says.
and so many others!