Today is 10-13-13. Since there are only 12 months in a year, this is the most times the single number thirteen has shown up in a single date since the year 1913. I guess the record holder would be the thirteenth day of a month in the year 1313.
Some people think that the number 13 brings bad luck, and some don't. Some also believe that it is doubly bad if the thirteenth day of the month falls on a Friday. So, why is that number considered unlucky and some other number, say 8, isn't? How did this all get started?
Well, according to my book "Dictionary of World Folklore", it all got started because there were 13 people present at the Last Supper and Judas Iscariot went out and hung himself. A very common English superstition holds that if 13 people sit down for dinner one will die before the year is out.
Thirteen is also called the "Devil's dozen". There is also the Baker's dozen. The Baker's dozen seemed to have started back when bakers were fearful of being prosecuted for giving short measures of their baked goods. But don't any of you worry, you are all going to have a great day, you hear?