1. The fear of Friday the 13th is known as friggatriskaidekaphobia or paraskevidekatriaphobia depending on whether you prefer Norse (the former) or Greek (the latter) origins for your phobias. To claim the phobia, you must be able to pronounce it (just kidding).
2. In 2013, aside from today, there will be a Friday the 13th in December.
3. Lots of things besides Friday the 13th are considered unlucky. Check out this Life magazine slideshow titled, “A bad-luck guide to Friday the 13th.”
4. Debate surrounds the origin of Friday the 13th’s reputation. One theory: According to Wikipedia, French King Philip IV, having become envious of the Knights Templars’ fortunes, gave orders on Friday, Oct. 13, 1307, to arrest the knights and charge them with heinous crimes.
5. Another theory that explains fear of the number 13 goes back to Norse mythology, according to an article from National Geographic News. A Norse myth recounts a dinner party of 12 gods at Valhalla, their heaven. When the 13th, and uninvited, guest, Loki the Trickster, arrived, he “arranged for Hoder, the blind god of darkness, to shoot Balder the Beautiful, the god of joy and gladness, with a mistletoe-tipped arrow.” Balder died and the world grew dark.
6. Christian tradition also points to unlucky 13 in that Judas, betrayer of Jesus, was the 13th guest at the Last Supper.
7. Christian tradition also points to a reason for bad luck being associated with Friday – it’s the day of the week on which Jesus was crucified.
8. Yet another possible explanation for fear of the number 13 (triskaidekaphobia, in case you're wondering), is that witches reported gathered in groups of 13 in Roman times with the 13th member being the devil (National Geographic News).
9. Rapper Tupac Shakur was pronounced dead on Friday, Sept. 13, 1996.
10. The original “Friday the 13th” film turns 32 this year. The hockey mask didn't appear until the third installment, but we’re willing to bet old-school hockey masks and deserted summer camps still make your skin crawl.
11. There have been 12 installments of “Friday the 13th” films, with the most recent being from 2009. Rumors abound that a 13th edition is in the works.
12. If you have trepidation about Friday the 13th, rest assured you’re not alone. According to the aforementioned National Geographic New article, Donald Dossey, founder of the Stress Management Center and Phobia Institute in Asheville, N.C., estimates as many as 21 million people in the U.S. have a phobia of Friday the 13th.
13. If you’re one of those 21 million, stay inside and watch movies. Just avoid people wearing hockey masks and abandoned summer camps.