Electrons can be removed from some objects using friction, simply by rubbing one substance against another substance. There are many examples of objects becoming charged by friction, including a rubber comb through hair, and a balloon on a sweater. In both these instances, the electrons move from the second object to the first, causing the first object to become negatively charged and the second one positively charged. Friction between the tires on a moving car and the road cause the tires to become charged, and wind causes friction between clouds and air which causes clouds to become charged and can result in tremendous bolts of lightning.
Consider the following text:
Dorothy is riding an elevator. The elevator has bristles running up the side of the tracks so her jeans are rubbing against them. When he gets to the top of the elevator she accidentally brushes a piece of metal and gets a small electric shock from it.

Given the electrons are moving to Dorothy's jeans and subsequently Dorothy, has she become positively or negatively charged?