What’s the coldest thing you’ve ever said to someone in public?

For me, it was some guy who I confronted who was hassling a woman outside a grocery store. He gave me some guff about being afraid of him as I was walking away. So I turned around and said, “You think I’m being polite to you because you believe I’m afraid of you. But I’m being polite because otherwise I would just kill you.”

I think that got his attention as he didn’t say anything else when I turned around again. That was in 1998 or so.