Either "I'm in the lines! You got a problem, go tell your mama!" or

Marge: Well, everybody's got a fear of something.
Homer: Not everybody.
Marge: Sock puppets!
Homer: Where?! Where?! Aah! Aah!

Release the robotic Richard Simmons!

Is the Stonecutter's song out of the running? "Who robs cavefish of their sight?" is a awesome line.

Oh, I have, I have! I swear I will never wear any clothing made from an animal. [to himself] That can do an amusing trick.

Marge, you know that batting this lightbulb is the only thing that cheers me up after giving away those million-dollar greyhounds.

Virgil:
It's "act". A-C-T. Act natural. Please put fifty thousand dollars into this bag and act natural.

I did think about writing something like Nevr.  Yet my single favorite one-off character is the crazy old German guy wearing the Kaiser helmet on the groom's side for Mr. Burn's wedding.  This is just my standard response.

Pipe down, rub-a-dub!

He did build a Wonderbat as well as a Spice Rack.  And without his wisdom I never would have thought a wicker basket could hold up a car.

Nein

I got this scar sneaking under the door of a pay toilet

No, Gaelic

Woman: Now we'll see what the future holds.
Lisa: [gulps] The "Death" card?
Woman: No, that's good: it means transition, change.
Lisa: [relieved] Oh.
[the woman turns over another card]
Lisa: Oh, that's cute.
Woman: [gasps] "The Happy Squirrel"!
Lisa: [timid] That's bad?
Woman: Possibly. The cards are vague and…

where's my spy camera?

Homer: Sir, I need to know where I can get some business hammocks.
Hank: Hammocks? My goodness, what an idea. Why didn't I think of that? Hammocks! Homer, there's four places. There's the Hammock Hut, that's on third.
Homer: Uh-huh.
Hank: There's Hammocks-R-Us, that's on third too. You got
Put-Your-Butt-There?
Homer:…

I said pull my finger.

I'm sure I'll get along with your family. You've so thoroughly prepared me for the worst. As long as they're not squatting in a ditch poking berries up their noses…

Just walk around not wearing a helmet.

Your mission today is to go to the Brain-Slug Planet.