An urban legend is a story that is mostly false, but often based on a few real occurrences. Some urban legends are completely false and so outlandish that it is a miracle that anyone believes them. Yet for certain reason, these mythical stories seem to outlive their creators as well as the first few waves of people that hear them. The three main reasons for the long life span of an urban legend are familiarity, exciting mystery, and the incorporation of information made out to be fact.
Mostly these silly fairy tales stick with us because the people we hear them from tend to incorporate real life situations or surrounding things and people into the stories to replace outdated information. This way, urban legends are constantly being updated to have the same impact on people even though the time and setting has changed. A story tends to have a much bigger impact on someone when it involves someone or something they know. You could say it hits hard at home. For this reason, urban legends, because mostly false, are made to incorporate things the listener knows about or the listener's current surroundings. This anchor to reality forces the listener to rethink whether the story could be true or not and most of the time the listener will walk away believing every bit of it as if they had seen it on the six o'clock news.
Another reason for the long life span of such impractical myths is that they are mysterious. By nature, humans are excited by mystery and suspense, and this is what fuels the legend's fire. People tend to get a kick out of being excited by mysterious things, and of course, they want to give their friends the same experience. So, when the time and place is right, we recall a story, and we tell it to our friends, making sure to through in some things from the current surroundings. Even if those people listening have heard the story before, it sticks in their minds as if the fire has been refuel...