Many people get a kick out of a direct contact with AC power supply. To that end, people normally use U-shaped fragments of bare wire, paper clips or even usual metal forks. All these gimmicks are unreliable, short-lived and, most important, tend to cause a short circuit or even an inflammation in the wiring. The Vilcus dactyloadapter (adapter for fingers) was especially developed for people who like closing the electrical circuit with their own fingers. Vilcus does not consume power by itself, so it can be left plugged into the power outlet until the next session.
Sold from 1 april 2007 at ThinkGeek, related: Grow Your Own 1up Mushroom.