If you swim in the "don't talk to police" ocean, you discover versions of the comic dialog (well, it isn't really funny) when the cops have you in the interrogation room "with your consent":

You: Am I under arrest?

Cops: We just want to ask you a few questions so you can help us out. You are not a suspect.

You: So I'm free to go?

Cops: We just want to clear up a few things. You are not under arrest.

You: So I'm free to go?

Cops: Before you go, we want to ask a couple things.

You: So I'm free to go?

etc.