Joe Biden's mouth strikes again, but I just LOVE the reply.
You know, a similar sort of thing happened to me once during a rising argument with other people about China and Taiwan. They finally got flustered and demanded repeatedly to know, "Do you consider yourself Chinese or Taiwanese? Chinese or Taiwanese?" I just smiled sweetly and said, "I'm an American." That totally took the wind out of their sails ... and had the bonus of being true.