Is it kind of urban legend ...?
Well talk about someone saying "From a friend ... ..." or "really was ... ..." widens.
In most cases, there are many stories that buried without being propagated, especially on the spot.
However, some stories told by the creator or the speaker who experienced it are transmitted from person to person, compiled, and sometimes life is blown in.
It sometimes deviates from the story of creation, it is told as something actually happened somewhere by someone, and there is something that will eventually become a reality.
And the content that the narrator told is unexpectedly told as a common experience.
When a strange story that you guys someday also propagates somewhere, someone's feelings are recruited, the story becomes one truth when it is a shared experiences of an indefinite number of people.
This is the process until a curse is completed.
Curses are something that one person's thoughts will be completed.