"What's blue in your nose?"

To this day, I still don't know. It could have been chalk, marker (yuck), crayon (ouch)...who knows? I was changing my son's diaper one afternoon a couple of years ago and happened to notice a little blue spot just below his nose. I went to rub it off and that's when I noticed that inside his nose was blue too. Taken aback I asked him this question, really hoping to get an answer because I was quite curious, but all I got were giggles. I guess it will forever be a mystery...