One of our favorite responses to questions like “Who is who?” or “Which one are you?” is something like “Um, wait. Today is Friday, right? Then I’m Jan.”
People actually believe this, folks! We know other twins who say they honestly don’t know; others say they aren’t twins at all, but actually five(!) months apart – and people don’t even stop to think about the impossibility of that.
Some people are just asking for it :) :)