To demonstrate static electricity through expanding stockings.
When the air inside a room is dry and warm static electricity can be demonstrated by pressing the toe of a nylon stocking against the wall. With your other hand stroke the stocking rapidly several times with a transparent polyethylene bag. Then hold the stocking in the air and observe it fills out as though an invisible leg were inside. Due to the fact that like charges repel each other, the sides of the stocking expand. This is due to a strong static charge on the nylon stocking.