Oh and another fact about Friday the 13th.

"At dawn on Friday, October 13, 1307, scores of French Templars were simultaneously arrested by agents of King Philip, later to be tortured in locations such as the tower at Chinon, into admitting heresy and other sacrilegious offenses in the Order. Then they were put to death." - Wikipedia

That is a reference I usually mention when talking about negative connotations of Friday the 13th.

That particular date had a ton of numerological significance if you are into that kind of thing.