Today is Friday the 13th, the third and final Friday the 13th of 2012. The last one fell in April, exactly 13 weeks ago. The first was in January, exactly 13 weeks prior to that.
So if you suffer from paraskevidekatriaphobia — letter soup meaning "fear of Friday the 13th'' — you're in luck: this is the last one until 2013.
Some experts tie the fear of the number 13 to a Norse myth about 12 gods having a dinner party at Valhalla, their heaven. In walked the uninvited 13th guest, the mischievous Loki, who later arranged for Hoder, the blind god of darkness, to shoot Balder the Beautiful, the god of joy and gladness, with a mistletoe-tipped arrow.
He did. The earth went dark. It was a very bad day.
Others attribute it to Judas, the apostle who betrayed Jesus, who was the 13th guest to the Last Supper. Ancient Romans claimed that witches gathered in groups of 12. The 13th supposedly was the devil.
If it sounds goofy, maybe it is. But try to find a high-rise building or a hospital with a 13th floor, or an airport with a 13th gate. Chances are you won't.
The phobia about Friday seems to be rooted in biblical references. Jesus was slain on a Friday, and Cain is believed to have slain Abel on Friday the 13th, and Eve supposedly tempted Adam on a Friday.
Just to be on the safe side today, throw some salt over your shoulder, don't step on any cracks and stay clear of black cats.