>Blank stare< "My name isn't Sue, it's Betty."
"What? Of course it's you, Sue. We ride the same train every morning!"
"I've never seen you before today, sir, and I've just recently moved here."
>Confused look< "No no, that can't be right."
"Do you mean to imply, sir, that you know my life better than I myself do?"
"No, that's not what I..."
"What a strange one he is!" >Walk to a different car<
Ah, my fantasies about how to deal with this kind of thing. They may not be polite, but they would be satisfying.