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.
75
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.
49
Many believe that if all of the candles on a birthday cake are blown out with one breath, while making a silent wish, the wish will come true.
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An acorn at the window will keep lightning out
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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.
70
Once a wedding ring has been placed on the finger, it is considered bad luck to remove it.
117
Placing keys on a table is considered unlucky. (Sweden)
3
If you catch a falling leaf on the first day of autumn you will not catch a cold all winter.
394