If the first day of the month falls on a Sunday, then the 13th of that month is a Friday!! :O
(Next one coming up is September)
Many theories exist on why Friday the 13th is considered unlucky, including but not limited to:
- 12 is considered a complete number, reflected in the twelve months of the year, twelve hours of the clock, twelve gods of Olympus, twelve tribes of Israel, twelve Apostles of Jesus, the 12 successors of Muhammad in Shia Islam, twelve signs of the Zodiac, etc., whereas the number thirteen was considered irregular, transgressing this completeness.
- Due to the Last Supper, having thirteen people seated at the table results in death for one of the diners
- Friday is traditionally considered an unlucky day since at least the 14th century. This maybe leads back to the fact that Jesus is believed to have been crucified on a Friday.
- According to one author, Friday and 13th combined together do not appear in texts until the novel Friday, the Thirteenth was published in 1907 (it's about a stock broker that decides to bring down Wall Street on that day)
In Spanish-speaking countries, Tuesday the 13th (martes trece) instead of Friday is considered bad luck!
info source: http://en.wikipedia.org/wiki/Friday_the_13th
picture source: http://clearguitar.deviantart.com/art/Happy-Friday-the-13th-208653183