Urban legends perpetrate a type of folklore, endlessly circulated by word of mouth, repeated in news stories and distributed by email. People frequently recount such tales as having happened to a "friend of a friend".
Some of the stories have survived for a very long time, having evolved only slightly over the years, as in the case of the story of a woman killed by spiders nesting in her elaborate hairdo. Other, new stories reflect modern circumstances, like the story of the man on a business trip being seduced by a woman and waking up the next morning minus a kidney surgically removed for transplant. One of the most famous is of alligators living in the sewer after being flushed down toilets when they grow too big to be kept as pets.
Some urban legends actually have a basis in true events, such as the case of the young man shooting bullets into a large saguaro cactus and being killed when his gunfire severed the trunk, resulting in the falling plant crushing him. Even when essentially true, however, the stories often become distorted by many retellings after the original event.