No, not the film. The day. It's tomorrow.
A day universally associated with bad luck, but for no clear reason that anyone can define. Many say 'it has its roots in Christianity' but know no more.
There are a few reasonable explanations for why this day is considered unlucky. The number 13 has long been associated with witches' covens, particularly those who prefer the darker side of the Pagan beliefs. Most of the old tales of witches (dancing naked in the moonlight, flying on brooms, sailing in sieves, the coven of 13, and much of what is now absorbed into modern 'witch' culture) is a load of rubbish. It stems from stories made up by accusers, embellished by lawyers, and forced from the lips of the accused under tortures so appalling thier minds could not focus. They would say anything - absolutely anything - the torturers wanted to hear.
Few of those accused were, in fact, witches. Everything they said was made up to stop the pain. The real witches, those few who were tried, were not evil. They were healers, herbalists, homeopaths. They had no means to curse or harm anyone, as should be obvious. If they had such powers, wouldn't their tormentors all be turned into toads?
Why Friday? There is one strong link, and it's also associated with accusations of witchcraft.
The Knights Templar, subject of so many wonderful and bizarre conspiracy theories, were originally intended to protect travellers to Jerusalem, back when it was in Christian hands from 1118. The romantic tale of the 'nine knights' isn't quite what it seemed. A knight didn't travel alone. Each had a small army with them.
Anyway, once Jerusalem was lost, the Knights Templar had no definite purpose. They had, over the two hundred years of their prime, become incredibly rich. The King of France owed a lot of money. Many of the Templars were in France. So the King (and his puppet Pope) decided to make up a load of nonsense, accuse the Templars of heresy, and, basically, steal all their money.
The Knights Templar were expertly taken, in their sleep, all at once. Those who weren't immediately killed were tortured, some for years, and finally burned at the stake. They had to be tortured because the King needed to show a decent pretense at following the law. He needed confessions. They didn't need to be true.
This heinous act took place on Friday, October 13th, 1307.
Is this the origin of Friday 13th as an unlucky day, perhaps? Or does anyone know of an earlier tale, which would make this one simply a vindication of the terrible date?