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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Two people breaking a wishbone is said to lead to good luck for the person with the larger piece.
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Pirates believed that piercing the ears with such precious metals as silver and gold improved one's eyesight.
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An acorn should be carried to bring luck and ensure a long life.
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It's bad luck to leave a house through a different door than the one used to come into it.
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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 a hat on the bed is, apparently, bad luck. (South Carolina)
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