There are many old books with curious old superstitious practices outlined. It can be fun to find the modern translations of theses and see if you can find any similarities with the superstitions of today.
The following curse is translated into modern English. It comes from "Alaricum's Book of Ancient Wisdom". I think you will be amazed at how many people still follow this little act of so called magic.
To stupefy your enemy and cause him to bring harm unto himself thou must use the Sign. Form a Sign large enough for thine enemy to see. The sign must have sides in the number of Saturn, that is to say eight. The color of the face of the sign must be the sacred color of Mars, the God of War, prepared from ochre and rust. On a pole established at a crossing of roads, where the mystical powers flow most strongly, affix the sign such that the face of the sign is turned toward the direction from whence thine enemy comes.
On the Sign, write in purest white letters the words "Sanitas -- Tumultus -- Oblivio -- Pestifer" having the meaning that the enemy shall lose his intelligence and wits and in all ways shall behave in a manner harmful unto him self. If the size of the sign prohibits writing the entire words, thou may write only the initial letters of each word.
On seeing the sign, thine enemy will stop and, being dazed by the arcane forces summoned there, shall be unsure of how to proceed. The enfeebled mind will then move forward into the crossroads when it shall cause him the most harm.