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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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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A single magpie is considered a sign of bad luck. A Guide to the Scientific Knowledge of Things Familiar recites an old proverb concerning the incidence of bad weather when magpies forage alone and a possible scientific explanation for this.
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Once a wedding ring has been placed on the finger, it is considered bad luck to remove it.
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Amber beads, worn as a necklace, can protect against illness or cure colds.
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Placing keys on a table is considered unlucky. (Sweden)
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If one walks underneath an open ladder it is said to bring bad luck. Sometimes it is said that this can be undone by immediately walking backwards back underneath the ladder.
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