“Oh, you’re form Earth… Do you know Richard Dreyfuss?”
(This is a so-so joke of mine based upon my experiences of people always asking if I know so-and-so when they find out I’m from New York City. New York is a big city; we don’t all know each other. And Richard Dreyfuss because he entered the space ship in Close Encounters of the Third Kind, so it’s safe to assume all aliens would know him, don’t you think?)
Followed by, of course: "Do you remember us from that Star Trek episode?"