Friday The 13th Superstitions: Where'd They Come From?

Today is Friday, May 13, 2011 -- the only Friday the 13th of 2011.

Friday the 13th happens at least once a year due to the modern calendar. Like last year, there's just one this year, but watch out: there are three in 2012 (January, April, July).

When you combine an historically unlucky day (Friday) with an unlucky number (13), all sorts of weirdness is bound to ensue. Hence the obsession with Friday the 13th.

Historically, some unlucky events are believed to have occurred on the day too. French King Philip IV rounded up hundreds of monks and tortured them for heresy on Friday, October 13, 1307. Some say Jesus Christ was crucified on Friday the 13th. More recently, on Friday, March 13, 1992, an earthquake in Turkey killed nearly 2,000 and left 50,000 homeless.

The No. 13 itself has driven people crazy for centuries, in large part due to Friday the 13th. Some people are so obsessed that triskaidekaphobia was born -- the fear of the number 13.

That fear has led the human race to make some strange decisions. Here are 13 examples. Vote on the most ridiculous and be extra careful today!

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• No room in the inn

  Hospitals and hotels regularly have no room number 13.

• On the street

  Many cities don't have a 13th Street or a 13th Avenue. This city tempted fate.

• Blame your parents

  If you have 13 letters in your name, you're said to have the devil's luck. Like, this guy (Charles Manson).

• Checking in

  Many airports skip the 13th gate.

• Aisle omission

  Airplanes have no 13th aisle.

• Numero...?

  Italians omit the number 13 from their national lottery.

• Unlucky height

  More than 80% of high rises lack a 13th floor

• One solution

  On streets in Florence, Italy, the house between number 12 and 14 is addressed as 12 and a half.

• Hangman's noose

  Traditionally in hangings, there are 13 knots in the noose and 13 steps leading up to the moment of death.

• Dinner luck

  French President Nicolas Sarkozy may know that in France, socialites called quatorziens (fourteeners) make themselves available as 14th guests to keep a dinner party from an unlucky fate.

• Space travel

  Many say the No. 13 pointed to the ill-fated mission to the moon, Apollo 13.

• It's in the cards

  Tarot Card number 13 is the Death Card, depicting the Grim Reaper.

• Ancient ties

  Some say that the Babylonian Code of Hammurabi (circa 1780 B.C.E.) is to blame for the No. 13 woes since the 13th law is omitted.