Walking Under a Ladder
It's common sense to avoid walking under av open ladder for fear of something falling on you, but there are superstitions reasons for doing so as well.
Consider the shape of an open ladder; a triangle that signifies life to some. When you walk though the triangle, you are tempting the fates. You may also awaken spirits that live within the triangle (including evil spirits who may not be happy with the disturbance) .
If you accidentally walk under a ladder, you can counter the bad luck by placing your thumb between your index and middle finger.