1. To prepare for the trick, hard-cook an egg. Place it in a small pot, with cold water to 2 cm (1 inch) above the egg, cover it with a lid, and heat until the water boils. Remove the pot from the heat and let sit for 20 minutes then rinse the egg under cold water right away. This will prevent a greyish ring from forming around the yolk. Now you're ready for the trick.

2. With a friend watching, hold the hard-cooked egg in one hand and the uncooked egg in the other and pretend to feel the eggs. (This won't tell you anything, but it will fool your friend.)

3. Spin the eggs on a table top with a flick of your fingers. The egg that spins best is the hard-cooked egg.

How the trick works: The yolk and white in an uncooked egg slosh around slightly so that it wobbles instead of spinning. The hard-cooked egg always spins smoothly.