An Italian composer died on that day and Jesus was crucified on a Friday and 13 guests were at the last supper. Also in harry potter prisoner of Azkaban Professor Trelawney was asked to Christmas dinner. She replies "if i join the table, we shall be 13! Nothing could be more unlucky! Never forget that when 13 dine, the first to rise will be the first to die!" then there was a study about car accidents vs. The week before and what they discovered was the likelihood of winding up in the hospital went up by 52% on Friday the 13th. There advice was to stay home on the unlucky day
This is like saying a black cat that crosses your path is bad luck to quote Groucho Marx "A black cat crossing your path signifies that the animal is going somewhere."
In short it's a silly thing to think black magic will happen or bad luck will happen because it's Friday the 13th.
It's all just silly superstition, I mean something bad could happen, but that's like saying if something bad happens on December 25th one time that it must be a cursed day. There's just no science to back the claim up, and I also don't believe in luck as it is anyways.
There is no science to back up the idea that this day is bad luck. The reason some people are convinced it is, is because they make it happen themselves. "Bad luck" happens everyday, but because this day is popularized, when bad luck happens, it feeds into people's imaginations that this day is actually a bad luck day. If you are always looking for bad luck, trust me, you will find it.