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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In some parts of England, rum is used to wash a baby's head for good luck.
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The superstitious symbolism of a black cat crossing one's path is dependent upon culture: some cultures consider this a sign of impending bad luck, while some cultures consider this a sign of impending good luck.
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There are numerous sailors' superstitions, such as: it is considered bad luck for a ship to set sail on a Friday, to bring anything blue aboard, to stick a knife into the deck, to leave a hatch cover upside-down, to say "pig", or to eat walnuts aboard.
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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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Two people breaking a wishbone is said to lead to good luck for the person with the larger piece.
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Placing keys on a table is considered unlucky. (Sweden)
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An acorn at the window will keep lightning out
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