As Monty Python..
M: Ah, Is this the right room for an argument?
A: I told you once.
M: No you haven't.
A: Yes I have.
M: When?
A: Just now.
M: No you didn't.
A: Yes I did.
M: You didn't
A: I did!
M: You didn't!
A: I'm telling you I did!
M: You did not!!
A: Oh, I'm sorry, just one moment. Is this a five minute argument or the full half hour?
M: Oh, just the five minutes.
A: Ah, thank you. Anyway, I did.
M: You most certainly did not.
A: Look, let's get this thing clear; I quite definitely told you.