English: Photographer's description: "You should get a charge out of this. My sliding grandson and static electricity combine to make a very humorous photo. Look for the shadow. It's priceless. This shot was completely candid. We tried to stage it at least another dozen times and it never worked again." This boy has been sliding down a plastic slide; the rubbing of his trousers against the slide has given him a static electrical charge. It's an example of triboelectricity.