This one is not a myth, and some of you may know about it: Take a roll of wintergreen Life Savers into a dark closet or somewhere else completely dark; bring a mirror or a friend. Bite on one with your mouth a little open so that you can see it. It will glow in the dark momentarily. Only works with wintergreen.
This is so true and cool! I went with a group spelunking many years (and pounds) ago, and everyone brought a roll of these things. When we stopped for lunch, we turned out all the lights. And back in the pre-cell phone days, that meant as dark as dark gets on this earth. We chomped those things in absolute blackness, and I'll tell you, life savers have never been so cool!