Smartest Simpsons Line/Joke

My nominee…

Marge: C’mon, Homer, Japan will be fun. You like Rashoman.
Homer: That’s not how I remember it.

A site has some clever ones:

Ich bin ein Springfielder." Homer: “Mmmmm. Jelly Donuts.”
Explanation: “Ich bin ein Springfielder” is an allusion to JFK’s speech in West Berlin in which he said, “Ich bin ein Berliner” (“I am a Berliner”). A “Berliner,” however, is not only someone from Berlin, but also a German word for Jelly Donut.

“My car gets fourty rods to the hogshead and that’s the way I like it”
A rod is an arcane form of measurement, equal to 512 yards or 1612 feet; a perch or pole. A rod is also farming measurement used in spacing the furrows in ploughed fields, of 16.5 feet. A Hog is a large, often old, car or motor-cycle in old U.S. Slang, and a hogshead is an old unit of measurement for liquids equal to 63 old wine-gallons, which is 5212 imperial gallons

Apu: I have come to make amends, sir. At first, I blamed you for squealing, but then I realized, it was I who wronged you. So I have come to work off my debt. I am at your service.
Homer: You’re…selling what, now?
Apu: I am selling only the concept of karmic realignment.
Homer: You can’t sell that! Karma can only be portioned out by the cosmos. [slams the door]
Apu: He’s got me there.

there’s lot’s more.

Lisa: “Even Gore Vidal has kissed more boys than I ever will!”
Marge: “Girls, Lisa. Boys kiss girls.”

Slight nitpick: In German, to say “I am a person of Berlin,” one would say, “Ich bin Berliner.” The addition of ein, in “Ich bin ein Berliner,” is what changes the meaning to “I am a jelly dougnut.”

Acknowledged jackelope.

I will, repenting, submit another one:

Homer: No one in history has ever done anything this clever!
On the plan to get back Springfield’s Lemon Tree, stolen by Shelbyville, by parking the van illegally, so it is towed into the parking lot where the tree is kept, from which they all sneak out at night.

I’m sorry, I had to add another one:

Lisa: Oedipus is the one who killed his father and married his mother
Homer: Argh! who paid for that wedding?

Sorry jackelope, that’s an urban legend.

To keep busy during a teacher’s strike, Lisa builds a perpetual motion machine, which bothers Homer.

“Young lady, in this house we obey the laws of thermodynamics!”

The episode that was just on, where the Simpsons move into the church. When Santa’s Little Helper comes out in one of Lovejoy’s robes, and he’s wearing the Communion cup on his head, and Homer remarks: “Awwww, he thinks he’s papal.”

Actually, as I understand it, including the word ein did form a sentance that would usually be interpreted as refering to a jelly donut rather than a berlin resident. However, given the context, it is unlikely that anyone would have interpreted it that way in this instance. And as your site points out, it is a technically correct way to say “I am a Berlin resident”

from the second page of the linked article

(at Grandma Simpson’s return) Lisa: This is like something out of Dickens… or Melrose Place…

From the episode where Marge is trying to join the Country Club, Burns and Homer are playing golf. Homer hits it into a sand trap. When he gets there he is not sure what to do. Burns gets impatients and says “use an open-faced club, a sand wedge.” Homer says, “UMMMM! Open-faced club sandwich! AAAAAAAAAAAAAA”

Another…from the “Tomacco” episode (clever in it’s own right) When the Laramie people are trying to buy the rights and all the Simpsons huddle in private to discuss the deal.
Lisa: These people are making billions off the suffering of others.
Marge: Lisa’s right! We should ask for more money!

Lisa: Wow, mom! You’re got a larger endowment then Harvard!
Homer: Well, Lisa wins the award for best off the cuff remark.
Lisa: Actually, I caught a glimpse of then on the way to the bathroom.

:Two security guards frighten Homer. He cowers behind the Bill of Rights.:
Guard: I’m so sick of you people hiding behind the first amendment.

My personal fav:
Brevity is… wit.
-a sign

Homer going into the witness protection program and they’re trying to work with him on his new name:

G-Man, stomping on Homer’s foot: Hello, Mr. Johnson
Homer (looks at other agent and whispers): I think he’s talking to you.

A second for the Rashomon line. I’ve seen that episode probably a dozen times, but after I understood the reference it added a whole new dimension of humor.

I’ve never nitpicked anyone before, but it is actually Mr. Thompson, not Johnson.

One of my favorite sequences is as follows:

Marge: Im a little worried about Bart, I want to help but I’m afraid of smothering him.
Homer: Yeah, because then we would get the chair.
Marge: That’s not what I meant Homer.
Homer: Admit it Marge, it is.

The best part about that exchange is the completely bland, blase way Homer says it. If he’s said it in some aware, retorting way it wouldn’t have nearly as much hilarity.

(paraphrased)

Homer: Name one person who ever did ANYTHING without air conditioning?

Marge: Balzac

Homer: No need to resort to potty mouth, Marge!
(And though it is a simple minded joke, I always thought the open faced club sandwich offering was VERY clever simply for the writing process involved in coming around to a joke like that.