A: I saw what you did.
B: I didn't do anything.
A: Oh yes, you did.
B: What are you talking about?
A: You know what I'm talking about.
B: I don't have any idea.
A: You know what you did.
B: Maybe I know, but how could you know?
A: Because I was watching you.
B: Okay, I'm sorry I did it.
A: Don't drink milk out of the carton. Use a glass!
B: I promise I'll never drink out of the carton again.