Lethal Capacitor, power cord, empty pop cans.
Put a pop can in the obvious place. Plug in the capacitor to the power source. Turn on the capacitor, and turn the variac dial to 80. Press the "H.V. on" button. Wait for the meter on the front of the capacitor to read 2.7kV, and then press the "surge on" button.
Shows Eddy current in a loud and potentially dangerous fashion. This one is a crowd pleaser.
Beware: The resultant noise is quite loud, and will startle and scare small children, as well as cause slight ringing in the ears of anyone close by.
Before firing the capacitor, ensure that the path of the pop can is clear, just in case it explodes and flies.
DO NOT let anyone touch the pop can while the capacitor is plugged in, as the capacitor has been known to discharge on its own, with no warning.
If the capacitor is fired too frequently, the connector will fuse itself shut. In this case, unplug the capacitor and use the attached screwdriver to pry apart the connector.