Despite your mother's warnings that you will almost certainly shoot your eye out with that BB gun or slingshot or rubber band, less than 1 percent of the United States population has a prosthetic eye. Although we call these convincing fakes "glass" eyes, they've been made out of acrylic, a plastic, since World War II [source: Steinberg].
Like dentures, glass eyes aren't surgically implanted into the wearer's face. The glass eye is held into place by the upper and lower eyelids, and the prosthetic can be easily removed with a nifty suction device and cleaned using soap and water [source: Erickson Labs Northwest].
But with the right amount of force — say, a jarring left turn at 90 mph (145 kph) — an artificial eye can be unintentionally ejected from the owner's socket. This has happened at least once at Disneyland, and also at a U.K. amusement park called Blackpool Pleasure Beach, where the dredging of a park pond uncovered several sets of dentures, a wig and a glass eye [sources: BBC News, Lait].