This calendar-based superstition is rooted in a fusion of Christian theology and maritime pragmatism. In Christian tradition, Friday was associated with the crucifixion of Jesus, and according to some accounts, Adam and Eve were expelled from Eden on a Friday. These biblical connections contributed to the belief that the day itself carried inherent spiritual misfortune. Additionally, maritime authorities historically observed a spike in accidents occurring on Fridays, though modern analysts attribute this to rushed end-of-week departures rather than divine wrath. The Royal Navy once attempted to disprove the superstition by commissioning a ship named HMS Friday, laying her keel on a Friday, launching her on a Friday, and appointing a Captain Friday—only to have her (as the legend goes) vanish without a trace. While the story may be apocryphal, it reflects the widespread cultural power of the belief. Spanish sailors, too, viewed Friday—and Tuesday—as days of bad luck, drawing on historical calamities such as the fall of Constantinople.