Don't hang mistletoe on Friday the 13th
I have no idea why Friday came to be considered an unlucky day, but one of early stories which associates the number 13 with bad luck comes from Norse mythology.
The queen of the gods, Frigga, had made everything in creation swear that it would never harm her son, Baldur, who was the most beloved of all the gods. The one creature who did not so swear was the mistletoe plant, which Frigga regarded as harmless.
There was a feast in Baldur's honor. Twelve gods were there in all. And then the 13th showed up, Loki. To make a long story short, Loki tricked his brother Hother into throwing a dart made of mistletoe at Baldur, and it killed him.
The queen of the gods, Frigga, had made everything in creation swear that it would never harm her son, Baldur, who was the most beloved of all the gods. The one creature who did not so swear was the mistletoe plant, which Frigga regarded as harmless.
There was a feast in Baldur's honor. Twelve gods were there in all. And then the 13th showed up, Loki. To make a long story short, Loki tricked his brother Hother into throwing a dart made of mistletoe at Baldur, and it killed him.