This is a noise and vibration joke that works by making people think the envelope contains hatched rattlesnakes. The envelope looks like a real envelope containing 12 rattlesnake eggs.

You wind an elastic band around and around a washer inside the envelope and then the trap is set as the washer lies flat in the envelope.

When someone opens the envelope to look inside the washer can unwind and a loud rattle sound is produced as well as a vibration. It's quite scary and shocks the life out of you when you don't know its a joke and think there may be baby rattlesnakes which are venomous in the envelope!

  The person who sets it off won't know what has happened until you tell them that they've been had!

These are great fun for people of all ages to play with. Great to use at the office, in the pub, at school etc.