here's some trivia for you:
(these facts have not been verified by me, so if they are wrong blame the websites I stole them from)
According to Smithsonian Magazine "fear of the #13 costs American a billion dollars per year in absenteeism, train and plane cancellations, and reduced commerce on the 13th of the month."
Lizzy Borden uttered a total of 13 words at her trial.
There were 13 original colonies.
A witches coven consists of 13 members.
Tarot Card number 13 is the Death Card, depicting the Grim Reaper (although it is read as transition or change and not literal death).
There are 13 steps leading to the gallows and 13 knots in a hangman's noose.
13 feet which the guillotine blade falls.
The driver of Princess Diana hit pillar #13 at Place de l'Alma when she was killed in Paris, France.
13 people, Christ and his 12 disciples, were in attendance at the last supper. This is where the Christian belief ties in, making Friday a believed unlucky day, as the crucifixion occurred on a Friday.
E Pluribus Unum has 13 letters.
The US Seal has 13 stars, bars, feathers in the eagle's tail, 13 bars in one claw, 13 olive branches in the other.