Electrostatic Hair Raising
To demonstrate electrostatic repulsion in a dramatic way.
Van de Graaff generator with ground sphere, styrofoam block, victim.
While standing on a large styrofoam insulating block, touch your hands to the top of the Van de Graaff dome, then have someone turn it on. The fact that your hair stands on end is a result of the repulsion between charges of the same sign that collect on your hair.