Because, as screenwriters, we all love useless information...
1. Paranoid and afraid today, maybe so much you can't leave the house?? Then you have paraskevidekatriaphobia: that is, Fear of Friday The Thirteenth. Really.
2. Friday the Thirteenth is considered unlucky in English, German and Portugese-speaking countries. In Greece and Spain, it's Tuesday the 13th that's considered unlucky.
3. The film, Friday The Thirteenth had a budget of $700,000 yet made $39,754,601. Everything you could ever want to know about this or the many films that came after can be seen on this website, including scripts. Additional trivia: I have never seen any of them. It's true.
4. A lot of people believe that Friday the Thirteenth is considered unlucky because there is a deep-rooted fear of both the number thirteen and, more surprisingly Fridays, stemming from Christianity. Basically, Judas was the 13th disciple (and we all know what happened there) and Christ was crucified on a Friday. In addition, some Christians believe that Adam and Eve ate the apple on a Friday and Noah's flood came on a Friday too. Many early Christians refused to plan any sort of trip or major activity on a Friday as they believed they would be doomed from the start.
5. One of our very own bloggers Jason, not the guy in the hockey mask, has written a book about Friday The Thirteenth. Rock on.
6. The Bible is well known to consider numbers and their significance. The number 12 is considered a lucky number: 12=1+2=3 = physical reality. As a result, the number which follows 12 was thought to be evil.
7. On Friday 13 June 1997, The Stranglers staged a concert at the sold-out Royal Albert Hall, London, UK with an eighteen piece string orchestra called The Electra Strings. "Friday the Thirteenth" then is the recording of their songs there, which include Skin Deep and Golden Brown.
8. I like this one the best: another suggestion for Friday the Thirteenth being unlucky is that it comes from Norse Legend. Twelve Gods were having a feast in Valhalla and the mischievous Loki gatecrashed the party as an uninvited 13th guest and arranged for Hod, the blind God of Darkness, to shoot Baldur, the God of joy and gladness, with a mistletoe-tipped arrow. Baldur was killed and the Earth was plunged into darkness and mourning as a result.