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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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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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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In some parts of England, rum is used to wash a baby's head for good luck.
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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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Before traveling a person should, apparently, sit on their luggage. (Russian)
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Placing keys on a table is considered unlucky. (Sweden)
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