The idea came from this magic set I used to have, and it came with one of these. I thought it would be cool to replicate it using LEGOs!
How it works:
There is a small hidden tab underneath the box pictured above, it connects to a secret drawer that moves. When you don't hold the tab, the item you place in the drawer is in the secret drawer. you close the box, chant magic words, place your middle finger on the tab (secretly) and open the drawer. The item inside has disappeared!! The drawer you are looking at is a fake, and is, in reality, a shell for the real drawer with the item in it. If you try to place an item in the fake drawer, it will not close.
This is a great way to surprise your friends on April fools day!