Why Is Friday The 13th Considered Unlucky?

Black cats, walking under ladders, opening umbrellas indoors and Friday The 13th...all superstitious stuff that can eventually lead someone to OCD.

HEY...I was born on the 13th...and the number 13 has always been lucky for me. But why is it deemed unlucky to begin with?

The most popular belief is that Jesus was crucified on a Friday and there were 13 people at The Last Supper....but there are other, lesser explanations for it.

Or is it just an urban legend?

About.com attempts to explain why Friday The 13th is unlucky;
read their theory BY CLICKING HERE.

...and don't walk under any black cats or have any ladders cross your path today...  ;)