They can't know you

I was in my trailer, working on Godfather II or III in New York, and there was a knock on the door. The guy working with me said that John Gotti would like to meet Mr. Coppola. And I said, "It's not possible, I'm in the middle of something." There's an old wives' tale about vampires — that you have to invite them in, but once they cross the threshold, then they're in. But if you say you don't want to meet them, then they can't come in. They can't know you.

Francis Ford Coppola in an interview in Esquire