Although most of us would probably affirm that superstition’s role in Western culture is now a much diminished one, more a source of amusement than anything else, there are still those who allow their trepidation over particular days or dates to prevent them from engaging in their choice of activities. We may make jokes about Friday the 13th and only kiddingly instruct loved ones to exercise greater care on that day, but those who suffer from a fear of the number thirteen (triskaidekaphobia) or a fear of Friday the 13th (paraskevidekatriaphobia) may genuinely feel limited by the rumored potential for ill luck connected with the date.
Superstitions regarding Friday the 13th are not nearly as old as most people tend to think. The belief in Friday the 13th as a day on which Murphy’s Law reigns supreme and anything that can go wrong will go wrong appears to be largely a 20th century phenomenon. (The claim that the Friday the 13th superstition began with the arrest of the final Grand Master of the Knights Templar, Jacques Demolay, on Friday, October 13, 1307, is a modern-day invention.)
These days, however, one is unlikely to get so much as a free latte out of the day. Sanguinity comes at a price.
For more information on the origins and history of Friday the 13th, try here and here.