Paraphrased,
Homer: Lisa would you like a hamburger?
Lisa: No.
Homer: How bout a chicken leg?
Lisa: Do you have any food that wasn’t brutally slaughtered?
Homer: Umm, I think the veal died of loneliness.
Lisa: (whilst ogling Nelson) “He’s like a riddle wrapped in an enigma wrapped in a vest. Sure is ugly, though.”
When Homer became a celebrity gopher, and Ron Howard was a guest…
RH: Homer, you smell like grass and vodka.
Homer: It’s a drink I made myself, it’s called a lawnmower. You want one?
RH: (pause) yeah, alright.
later in the same episode, Ron calls Homer on the phone
RH: Hey Homer, we need more vodka.
Smithers: Shall I send out for Chinese sir?
Burns: No, those people are all gristle.
Milhouse: Then why did I have the bowl, Bart? Why did I have the bowl?
One of Bart’s blackboards:
I have neither been there nor done that.
I have neither been there nor done that.
I have neither been there nor done that.
I have neither been there nor done that.
I have neither been there nor done that.
I have neither been there nor done that.
I have neither been there nor done that.
I have neither been there nor done that.
There are so many, but these are the ones that come to mind first:
(Clancy Wiggum) “Bake 'em away toys”
(very frustrated Witness Protection agent) “Now when I say ‘hello Mr. Thompson’ and step on your foot you smile and nod”
(Luke Skywalker singing dinner theater) “Luke be a Jedi toniiiiiiiight”
and finally…not a quote…when Joe Namath was ending the episode with a big grin. then stops grinning abruptly…then goes back to the big grin. My husband and I make that face to each other sometimes and we always crack up.
I love the Simpsons. 
ps I wanted to mention Homer’s stage whisper to the other witness protection guy:
“I think he’s talking to you”
“i noticed your house smells like feces… and not just monkey feces”
Kang: We must go forward, not backwards. Upwards, and not forward! And always twirling, twirling, twirling towards freedom!!
When Apu had to live with the Simpson’s after losing his job at the Quick-E-Mart he sang a song about how happy he was. After the song the family hears Apu crying on the roof.
Homer: Hey! he lied to us through song, I hate when people do that!
As seen as someone’s sig here:
“Why wont those stupid idiots let me into their crappy club for jerks?”
and
“You tried your best, and failed. Never try.”
by HJS.
and from Bart and Lisa- “Hard work made us quit.”
another from Homer, in the flash forward at the Indian casino-
“That lying, rail-splitting, theatre-going freak!” when he discovers Lincoln’s “gold”.
Don’t get me started, we could be here a while.
Homer is bargaining for a Krusty doll or something in one of the Halloween episodes I believe(?). Anyway, Homer is in a mysterious shop ala Gremlins and has this conversation with the proprietor…
Shopkeeper:<grimly> Take this object, but beware – it carries a terrible curse.
Homer: Ooh, that’s bad.
Shopkeeper:<(brightly> But it comes with a free Frogurt!
Homer: That’s good!
Shopkeeper:<grimly> The Frogurt is also cursed.
Homer: That’s bad.
Shopkeeper:<brightly> But you get your choice of topping!
Homer: That’s good!
Shopkeeper:<grimly> The toppings contain potassium benzoate.
Homer: <dumbfounded, says nothing>
Shopkeeper: That’s bad.
Homer: Can I go now?
That is some good stuff, though not exactly a “quote” now that I think about it-- oh well… 
Bart: How’re those berries, Ralph?
Ralph: They taste like…burning. (Collapses on ground, moaning)
Smithers (I think), on golf course: Use an open-faced club! A sand wedge!
Homer: Mmm…open-faced club sandwich…
Marge: There’s no shame in being a pariah.
Homer, after breaking promise to get rid of his gun: But, Marge, I swear to you! I never thought you’d find out!
Future fat Bart: Ah wash mahself with a rag on a stick.
Audience claps.
I thought it was McBain who said ths, playing the part of Radioactive Man
McBain:“Aah, My eyes! Ze goggles, zey do nothing!”
And another
<Mcbain breaks out of an ice sculpture standing in the middle of a table>:“Ice to see you”
LMAO
Rick
Another from the late, great Phil Hartman (as Troy McClure):
[in song]
I hate every ape I seeeeee
From chimpan A to chimpan Zeeeeeeeeeee
You’ve finally made a monkey out of meeeeeeeeeeeee!
Rainer Wolfcastle is McBain. McBain is a movie character, Ranier is an actor.
Marge: Do you just follow my husband around everywhere?
Hot Dog Vendor: Lady, he’s putting my kids through college.
‘Duffman can’t breathe. Ohhh no.’