Wish I could remember how to make rattlesnake eggs, cuz it was always a winner on April Fools day & I never pulled it on any of my kids. The severed finger in a box got old for them years ago.
Anyway, speaking of zoo mishaps, did anyone around here post anything about the two thousand gallon monkey dung drop on one of Milwaukee's freeways, bout a week ago?
You need a rubber band, bobby pin or heavy paper clip, a knickle and a small envelope. Open the bobby pin or paper clip until you have formed a rough V or U shape making sure that the open ends are roughly parallel to one another. Slip the rubber band over the open ends of your bobby pin/paper clip. If the rubber and will not stay in place you probably need a smaller one or you need to open your 'V' or 'U' shape up a tad more. Put the knickle in the center of the rubber band and start turning it end-over end winding it inside the rubber band as you go. Make sure you wind it quite a bit as you'll need enough tension to execute the 'rattle' when they open the envelope.
Now, with your knickle all wound up, insert the entire contraption in the envelope making sure the device does not unwind. Close your envelope and then lay it on the table. If the knickle doesn't automatically unwind then your trap is set.
Enjoy!