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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Placing a hat on the bed is, apparently, bad luck. (South Carolina)
9
According to an age old custom, carrying a dead shrew in your pocket wards off rheumatism!
24
Before traveling a person should, apparently, sit on their luggage. (Russian)
117
If you catch a falling leaf on the first day of autumn you will not catch a cold all winter.
394
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
Placing keys on a table is considered unlucky. (Sweden)
3
An acorn should be carried to bring luck and ensure a long life.
115