But not everyone walks around with a photographic memory of the calendar, such that they can recite the next occurrence of Friday the 13th. As Mr. Vorhees shows us, some careers actively rely on ...

Triskaidekaphobia simply means fear of the number 13. There can be as many as three Friday the 13ths in a single calendar year, such as in 2009 or 2012. This year the day will also occur three times.