Here is a simple experiment that will teach you an important electrical
lesson: On a cool, dry day, scuff your feet along a carpet, then reach your
hand into a friend's mouth and touch one of his dental fillings. Did you
notice how your friend twitched violently and cried out in pain? This
teaches us that electricity can be a very powerful force, but we must never
use it to hurt others unless we need to learn an important electrical lesson.
It also teaches us how an electrical circuit works. When you scuffed
your feet, you picked up batches of "electrons", which are very small objects
that carpet manufacturers weave into carpets so they will attract dirt.
The electrons travel through your bloodstream and collect in your finger,
where they form a spark that leaps to your friend's filling, then travels
down to his feet and back into the carpet, thus completing the circuit.
-- Dave Barry