The number 13 has long been considered unlucky. In numerology, 12 is considered complete (12 hours, months, zodiac signs) - and 13 is irregular. There were also 13 guests at The Last Supper (the 13th being that traitor Judas). Jesus was also crucified on a Friday.
A Dutch study from 2008 apparently showed that fewer accidents and reports of fire occurred on the date as people were generally much more cautious.
The beliefs surrounding black cats vary around the world, with some cultures considering them to be lucky and others a bad omen. The most widespread Western belief is that if a black cat crosses your intended path, bad luck will befall you.
Black cats have long been associated with witches, and during the Middle Ages these superstitions even led people to kill them. This was then said to increase the population of rats and hence the spread of the Black Death (Bubonic Plague).
Breaking a mirror
One of the longer sentences dished out by Lady Luck, the superstition follows that breaking a mirror will leave you doomed for seven years. The reflection is said to represent the soul, so damaging a mirror corrupts the soul of the one that broke it.
Some believe that the reason for the length of the punishment is that the Romans (the first glass mirror-makers) thought life renewed itself every seven years, so the soul wouldn't be fully restored until the next cycle had passed.
Opening an umbrella indoors
Back in Ancient Egypt when umbrellas were used as protection against the sun, they were designed to capture Nut's (the goddess of the sky) essence. To open one indoors would also be to insult Ra and invite his wrath on everyone in the household.
Another myth surrounding the superstition is that it was invented specifically to cut down on the number of accidents that sprang from the pointy and dangerous metal spokes on umbrellas in Victorian England.
To see a single Magpie is considered unlucky, so you may hear people greeting the bird with 'Hello Mr Magpie. How/Where is your wife?'
Magpies are often seen as sneaky due to their penchant for shiny objects, such as jewellery and coins, their lack of a pretty singing voice, and their habit of eating the eggs from bird nests.
In Scotland they're considered a sign of impending death, but in China spotting one is regarded as good luck.
Generally they're not all bad though, only when alone:
The old rhyme goes:
'One for sorrow, Two for joy, Three for a girl, Four for a boy, Five for silver, Six for gold, Seven for a secret never to be told.'
Back in the day, long before processed meals were invented, salt was an extremely rare commodity and so to spill it was considered a waste of money. As a valuable preservative, it was also linked with longevity so some cultures believed that spillage could affect your own health.
If you look closely at Leonardo da Vinci's The Last Supper, you might also spot that Judas has spilled the salt.
A German proverb holds that 'whoever spills salt arouses enmity', with the best antidote being to toss a pinch of the spilt salt over your left shoulder, into the face of the Devil who lurks there.
Full Moons are traditionally linked with temporary insomnia and insanity due to the folklore that madness can occur in cycles with the moon, hence the term lunatic or lunacy. It was also thought that to sleep in direct moonlight caused madness or blindness.
The full moon is of course associated with lycanthropy as the mythological werewolf is said to appear whenever one appears...A study by the Bradford Royal Infirmary even found that there was a significant increase in animal bites during a full moon over a certain period.
Treading on cracks in pavement
'Step on a crack, break your mother's back'
The superstition of stepping on cracks in the pavement is said to originate from an ancient fear of letting the soul out of the Square, as the four corners are an ancient symbol of balance and perfection. It also makes for some interesting walking habits.
Never say 'Macbeth'
According to a theatrical superstition called the Scottish curse, speaking the name Macbeth before a performance will cause tragedy - as a result the lead character is often referred to as the Scottish King. Those who believe in the curse claim that real spells are cast in the three witches scene.
Productions of Macbeth are said to have been plagued with accidents, many ending in death. The legend of the curse dates back to the premiere of the play when an actor died because a real dagger was mistakenly used instead of the prop.