Placing a hat on the bed is, apparently, bad luck. (South Carolina)
9
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.
75
Placing keys on a table is considered unlucky. (Sweden)
3
Once a wedding ring has been placed on the finger, it is considered bad luck to remove it.
117
If one walks underneath an open ladder it is said to bring bad luck. Sometimes it is said that this can be undone by immediately walking backwards back underneath the ladder.
105
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
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.
298
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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