As played with a bundle of silk thread, as you do.
This gem comes to The Blog of Phyz from Inderkum's Jessica Downing, an upbeat, resourceful teacher at the most amazing high school in America.
It's a nice sequence of polarization, charging, repulsion, and discharging—rinse and repeat. It's like a puppy playing fetch.
This video below is slow-motion. This link will take you to the normal-speed version.
Van de Graaff Demo