When you speak of bad luck, it is said that one should always knock on wood. Also knocking when speaking of good luck apparently helps with having good luck. This is an old Celtic tradition related to belief of wood spirits.
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Some motorcycle enthusiasts hang a biker's bell from a portion of their bike to protect themselves from evil road spirits.
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An acorn at the window will keep lightning out
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Before traveling a person should, apparently, sit on their luggage. (Russian)
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Many believe that if all of the candles on a birthday cake are blown out with one breath, while making a silent wish, the wish will come true.
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It is bad luck to put new shoes on a bed (or a table) (comes from the tradition of dressing a corpse in new clothes and shoes and laying them out so everyone can give their respects) - (UK)
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Placing keys on a table is considered unlucky. (Sweden)
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Placing a hat on the bed is, apparently, bad luck. (South Carolina)
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