There are several reasons why Friday has been considered the most unlucky day of the week. Jesus Christ was crucified on a Friday. Friday was traditionally the day when criminals were executed. According to one superstition, if you cut your nails on a Friday, witches would pick up the pieces and turn you into a witch yourself.
Friday was also known as ‘Tip Tod’s Day’, meaning the Devil’s Day. In earlier times, sailors didnt like putting to sea on Friday. And it was also said that work started on a Friday was never finished ( which sounds like a good excuse for taking Friday easy ).
Then there is thirteen. This has been an unlucky number in the Christian world ever since thirteen sat down to eat at the Last Supper on the night before Jesus Christ was crucified.