You've probably heard at one time or another that Wint-o-Green mint Life Savers sometimes flash when you bit down on them. Since this would require chewing with your mouth open, I have never seen it. But it happens. Smarter Every Day shows us what it looks like in slow motion.
The phenomenon is called triboluminescence, which is light generated by the energy of breaking chemical bonds. Cool Science explains it more thoroughly, and how you can try it at home. -via Boing Boing