Packets have a picture of a real rattlesnake and are labeled with loads of fake, but frightening warnings: "RATTLE SNAKE EGGS - CAUTION: To prevent hatching store in a cool, dry place."
Cool gag gift is nothing more than a device made from wire a washer and a rubber band. Twist it up and put it back in the envelope. When someone opens it up the rubber band comes unraveled and makes a noise when it snaps against the envelope. Directions are included.