Electric shock device

A friend of my fathers had a dry cell powered device with two metal handles you gripped while the operator slid a rod in a coil to increase voltage. the idea was to hang on till you couldn't. These drunks would hold on till the thing made their wrist muscles contract their hands into claws. How would you build this thing?

It sounds like they adjust the coupling between two coils - one with a lot of turns on it, attached to your drunk, the other wired to the mains AND ISOLATED FROM THE FIRST COIL. A slug between the coils would increase the coupling, and the voltage induced.

Wow! That does sound like it would be fun at parties!