Fear of Friday the 13th. It's a common superstition. Do you alter your behavior to avoid this "unlucky" day? I suppose I do, since I talk about it and joke about it all day. But I don't avoid normal activities because I think I'm in danger. Do you, "just in case"? The medical term for this fear is paraskevidekatriaphobia. Fear of the number thirteen is called triscadekaphobia or triscadecaphobia. When bad things happen on the 13th, or on Friday the 13th, people often make note of it and present it as evidence that the day is indeed unlucky. Once enough people believe it, it is self perpetuating. Was the Apollo 13 space flight doomed from the start, or did we just pay attention to the number because of the coincidence? The origins of the superstition are mixed, partly from Christian history, partly from Norse culture, and partly from other sources, such as the arrest of Jacques de Molay, Grand Master of the Knights Templar on Friday the 13th by King Philip IV of France in 1307. Perhaps instead of doing anything dangerous today, you should stay home and [playlistId=4249065&selectedItemId=4249047]listen to music[/playlistId] or rent an old movie or read a great book! You can find other interesting information about paraskevidekatriaphobia here and some good links about Friday the 13th here.