cracked:

This is a chemical called europium tetrakis, demonstrating the effect of triboluminescence. Eyes glazing over yet? Are you daydreaming of puppies already? All right, we’ll hype it up some: This is how you create a thunderstorm in a bottle by smashing things

The effect happens when crystals don’t bother to generate electricity or heat, but rather skip a step like the lazy crystal bastards they are and convert kinetic energy directly into light.

If you want to see it for yourself but you don’t have any europium tetrakis lying around (if you’re out, just ask the neighbor to borrow a cup!), the good news is that another, more common substance can do the same thing: sugar. Just sit in a dark room, put some sugar cubes in a blender, and watch the fireworks.

7 Mind-Blowing Chemical Reactions You Won’t Believe Are Real