Another theory is more specific to Catholicism. Traditionally, every Friday is sacred because Jesus died on a Friday. That's why many observant Catholics will fast and abstain from meat on Fridays year-round. With that in mind, the Friday before Easter Sunday, which commemorates Jesus' resurrection, is particularly meaningful, as it's the actual anniversary of his death. In remembering the sacrifices Jesus made for his followers' sins on this day, some will call it "good."