It is said that it originated from religious allusions: Judas, who betrayed Jesus, was the thirteenth disciple of Jesus; There is also a saying that every month, as long as 13, 12 witches will hold carnival night parties, and 13 Satan will appear at the climax of night parties, which will bring disaster to people. Therefore, Westerners are not only jealous of the day "13", but also the number "13". So people are disgusted with "13". Because Jesus was crucified on Friday, westerners generally don't hold activities on that day, which is both 13 and Friday.