A bezoar is a ball of swallowed foreign material (usually hair or fiber) that collects in the stomach and fails to pass through the intestines.
Chewing on or eating hair or fuzzy materials (or indigestible materials such as plastic bags) can lead to the formation of a bezoar. The rate is very low and the risk is greater among mentally retarded or emotionally disturbed children. Generally bezoars are mostly seen in females aged 10 to 19.