Why Friday 13th is considered a day of bad luck?

Today I bought a book for a half of the price- a very good deal for me. I have ever thought the combination of this day of the week /I am born on it/ and the number 13 – I am born on 12 and on 13 was my first day in life/is somehow artificially invented to frighten people .Are other that are thinking like me?
By the way I consider the 11.11 to be devil’s preferred combination as if he wants for ever to be first in destroying all he can.

It is a silly superstition.

Technorati Tags: , , , , ,