I'd have to say the "maybe they should fear you" scene, but for a different reason.

Pacino's delivery just makes it such a great "out of left field" come-back.

By deliberately saying it in such a childish way, he's mocking Connie's over-the-top seriousness. Great stuff.


Another good 'insult' from Michael Corleone; "you are what your are."

Having gone something like 2 years without watching those movies, I was actually under the impression I had invented that line myself, then realised where it was from when I watched Part III again.

"He's a cemetery mink. He lives down in a ribcage, in the dry leaves of a heart."