Paraskevidekatriaphobia

That's hard to spell, it means fear of Friday, the 13Th( today). The 13Th date which falls on any Friday of the year is considered to be unlucky, its a superstition. I didn't know it till today did you?.

Some facts:
Many places do not have 13Th street
Many buildings do not have a 13Th floor
Many airplanes do not have a 13Th row
Many ships will not start a voyage on the 13Th, particularly, Friday the 13Th.............

Read more here

http://urbanlegends.about.com/cs/historical/a/friday_the_13th.htm

http://en.wikipedia.org/wiki/Friday_the_13th