Rubber Egg

Play a hilarious joke on your friends: drop an egg and watch them first wince, then stand amazed as it bounces back up! Watch out though, as the egg is not a regular shape, so it may bounce off in unpredictable directions.  

Rubber eggs like these even fool chickens... they are often sold as a kind of decoy to encourage domestic hens to lay their eggs in the desired places. This egg is probably made from silicone rubber, a non-toxic synthetic rubber which would be suitable for use with animals and food items. It is non-reactive to most other substances, and has excellent resistance to extreme temperatures, so will not disintegrate or crack with long-term outdoor use. Silicones are synthetic polymers with elastic properties called elastomers. They are not true, natural rubbers. The extreme bounciness of synthetic rubber comes from the flexible structure of long chains of molecules in the polymer, which can expand and contract again when the material is under stress and then released, memorising and retaining its original shape.