Do not tempt fate by walking under a ladder
Some may think it instinctual to avoid walking under a ladder, and while it is common sense for your safety, it developed over the years into a bona fide superstition. The exact history of the practice is unknown, but some researchers have posited their own theories. The most common belief is attributed to the shape a ladder makes when opened or propped against a wall: a triangle. In many cultures, the triangle symbolizes life, and so walking through the shape signified tempting fate. This theory is thought to originate in Ancient Egypt.
Another idea concerns the ladder’s shape in regards to Christianity. Again, passing through a triangle, a symbol of the Holy Trinity in this case, was believed to be an insult to God and attracted the devil.
The other explanation put forward dates the superstition back to medieval times and execution methods. In 17th-century England, people who were deemed guilty and sentenced to death were forced to walk under a ladder on their way to the gallows, and a ladder was used as well to allow the condemned to climb high enough to reach the noose. The association with death is thought to have progressed into a general belief in bad luck.