An urban legend is a story, passed from person to person, about an event that is said to have really occurred. The story is phrased in believable terms, but the ending is usually horrifying, shocking, or humorous. By definition, urban legends are false—either completely made up or based on actual events but greatly exaggerated or distorted.

The term "urban legend" has been in use only since the 1930s, but the phenomenon has probably existed as long as human society has existed. People tend to believe and to pass on stories that are reasonable, interesting, and make a point. Folklore experts who study urban legends say that the accounts usually come from a credible source (a friend, relative, or coworker), have a narrative form (a story with characters and a plot), and contain elements of humor, caution, or horror.

One of the most common types of...