Is McCain a redhead?
Stolen from a commenter on reddit:
The next time someone says "I'm not voting for Obama because he's a Muslim," I'm going to respond "Well I'm not voting for McCain because he has long red hair.
They will, of course, be completely taken aback. That's when I'll say, "What, you mean that you're confused that I'm basing my voting decision on something that is not only a complete, verifiable lie, but that shouldn't even affect my decision if it were true? Now you know how I feel."