Don't Walk Under a Ladder

Walking under a ladder propped against a wall brings terrible bad luck. You must go around it, no matter how inconvenient. If you accidentally walk under one, you should cross your fingers until you see a dog.

A ladder against a wall forms a triangle, and in medieval Christian Europe, the triangle was a sacred symbol of the Holy Trinity. Walking through it was considered blasphemous. Earlier, in ancient Egypt, ladders were placed in tombs to help souls ascend to heaven — disturbing them was taboo.

Someone is working above you on that ladder. Walking underneath risks having tools, paint, or debris dropped on your head. It's genuinely dangerous. This is one of those rare superstitions where the practical reason is so obvious it's almost funny that we needed a supernatural explanation.

This one actually aged well. OSHA workplace safety regulations literally say don't walk under ladders. It went from folk superstition to federal law. Construction sites worldwide enforce this. Sometimes the ancient wisdom is just... correct. No supernatural explanation needed, but it took us thousands of years to admit that.