Socrates: Define, for me, a punch line.
Hippias: A punch line is at the end of a joke.
Socrates: Is it a punch line simply by virtue of being at the end of said joke?
Hippias: No, it must be an unexpected statement.
Socrates: Ah, but if you know that the punch line is about to arrive, how can it be unexpected?
Hippias: True. Therefore, there can be no punch line to any joke, for such a punch line is always to be expected.
Socrates: Exactly. Last night the exact same logical conclusion was told to me by your mother, while we had intercourse.
