This magic trick is advised to be done in a party where your target audience is the kids. I am not sure if any adult will fall into this trick but you can also try. This magic trick needs a box of crayons, a box of 8 is ideal. Hold the box of crayons behind your back and ask a kid to pick a crayon from it and put it in your hand.
Face your audience but your hands with the crayon are still behind your back. Tell them that you are trying to see the color of the crayon in their eyes and while doing that, scrape the crayon on your fingernail. Use the hand where you scrape the crayon on, perform a little wave of that hand so you can see the color.