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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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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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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Placing a hat on the bed is, apparently, bad luck. (South Carolina)
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Opening an umbrella indoors is said to result in 21 days of bad luck. Some traditions hold that it is only bad luck if the umbrella is placed over the head of someone while indoors.
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Placing keys on a table is considered unlucky. (Sweden)
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Amber beads, worn as a necklace, can protect against illness or cure colds.
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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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