There are cultural superstitions and individual obsessive -compulsive superstitions as well as those that overlap in religion. Here's a place to consider superstitions as prompts for stories.
Black cats, Friday 13th, walking under a ladder, all bad luck. Rabbit's foot good luck. Bad luck comes in threes, break a mirror for seven years bad luck, knock on wood, wish on wishbone, cross fingers for good luck, umbrellas open indoors bad.
Each country has its own superstitions. Pick a country and explore it's superstitions. Many are based on avoiding the evil eye of a bad person. In the middle east, tyng a red string around a baby's ankle protects it from the evil eye. Spitting three times when a child gets a compliment. 'Sprinkling bread soaked in water on a child's foreheod will prevent the evil eye.
People with obsessive compulsive disoder create their own unique superstitiosus rituals that are endless.
You know it when you see it or do it.
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