A Drop in the Bucket: An Unconventional Switch

 

The circuit on the left and the switch on the right.

The switch uses a jar of coins to complete the circuit. The positive side of the circuit is buried in the jar. When a coin attached to the other side of the circuit touches one of the coins in the jar, the circuit completes and the red LED gets power and lights up. Since all of the coins are made of metal, they all conduct electricity and pass the current between each other. This is why the circuit completes itself despite the fact that the two coins that the wires are attached to are not touching each other. 

The schematic for the circuit.

And the video showing the switch in action.