Paraskevidekatriaphobia

Paraskevidekatriaphobia:
A morbid, irrational fear of Friday the 13th. Therapist Dr. Donald Dossey, whose specialty is treating people with irrational fears, coined the term. He claims that when you can pronounce the word you are cured.

There are many theories as to the origin of Friday the 13th being considered an unlucky day.

One theory, recently offered up as historical fact in the novel The Da Vinci Code, holds that it came about not as the result of a convergence, but a catastrophe, a single historical event that happened nearly 700 years ago.

The catastrophe was the decimation of the Knights Templar, the legendary order of "warrior monks" formed during the Christian Crusades to combat Islam. Renowned as a fighting force for 200 years, by the 1300s the order had grown so pervasive and powerful it was perceived as a political threat by kings and popes alike and brought down by a church-state conspiracy, as recounted by Katharine Kurtz in Tales of the Knights Templar (Warner Books: 1995):

"On October 13, 1307, a day so infamous that Friday the 13th would become a synonym for ill fortune, officers of King Philip IV of France carried out mass arrests in a well-coordinated dawn raid that left several thousand Templars — knights, sergeants, priests, and serving brethren — in chains, charged with heresy, blasphemy, various obscenities, and homosexual practices. None of these charges was ever proven, even in France — and the Order was found innocent elsewhere — but in the seven years following the arrests, hundreds of Templars suffered excruciating tortures intended to force 'confessions,' and more than a hundred died under torture or were executed by burning at the stake."

Some other theories can be found here....or here.

I'm not superstitious myself so have no fear of Friday the 13th. In fact it will almost certainly be a better day than today--Thursday the 12th--because at work "anything that could go wrong did go wrong", thus verifying "Murphy's Law" ! In fact it made me feel a bit like acting like that fella Jason from "Friday The 13th" as seen below: