That is fear of Friday the Thirteenth if the term was Greek to you! If you do, you are not alone. The Stress Management Centre and Phobia Institute in the U.S. estimates that losses to businesses on Friday the 13th is a whopping 800 to 900 million dollars. Many people in particular avoid flying on that day. Perhaps that is lucky for people on standby!
A National Geographic website claims that in the U.S. alone there are between 17 to 21 million who fear Friday the 13th. Statistics in Canada on auto accidents do not show any increase on Friday the 13th. Some insurers even say that claims drop because fewer people drive on that day.
There are varying theories as to the origin of the superstition. Some claim that Cain slew his brother Abel on Friday the thirteenth. Others say the superstition arose because King Philip the fourth of France arrested the Knights Templars on Friday Oct. 13th 1307. For much more see this CBC article. Some skeptics even schedule special events for Friday the 13th.