The phrase "Friday the 13th" rings alarm bells, not just because 13 is a number thought to bring misfortune, and Friday brings to mind a certain Rebecca Black who gained Internet notoriety by singing a song called Friday made up of her repeating the words "Friday", "partying" and "fun" over and over again.
For the superstitious, Friday the 13th is a day full of misgivings, and for cynics, a time for mocking age-old beliefs and traditions, some of which seem just plain ridiculous.
This time round, it is even more intense as the date coincides with a full moon. We might finally get the answer to the question: "What happens when a werewolf breaks a mirror?"
Friday and the number 13 are both already regarded as unlucky on their own. Put them together, and its a lethal combination of long-held superstitions and taboos.
No one knows exactly when the obsession with this particular date came about, or friggatriskaidekaphobia, as it is called in Greek. Frigga is the name of the Norse goddess which Friday is named after, while tris-kai-deka-phobia quite literally means "three-and-ten-fear".
What's wrong with 13?
It is thought that 13 is seen as an unlucky number, simply because 12 is the complete number.
In Christianity, Jesus had 12 disciples. In Shi'ite Islam, the Prophet Muhammad had 12 successors. The Buddhist cycle lasts for 12 years. There are 12 signs in the Zodiac, and 12 months of the year.
It is also thought that the concept of 13 being an unlucky number goes back to primitive man, who could not count beyond 12 since they had 10 fingers and two feet.
Now imagine their surprise when they found out they had 10 toes.
Thirteen was hence the extra number, the ugly oddball, the disruptive one who kept crashing a party he wasn't welcome to. And when they tried chasing him out, he turned into a monster and started destroying everything, and now everyone is scared of him. You get the idea.
In the Bible, there were 13 people present at the Last Supper, where one of Jesus' disciples betrayed him.
In Norse mythology, there was once a banquet where 12 gods were invited, but not Loki, the God of Mischief. So he crashed the party and wreaked havoc, which ended in the death of Balder, the God of Light and Purity. How's that for a tantrum.
So from now on you might associate Friday the 13th with hunky British actor Tom Hiddleston, who plays Loki in the Marvel Studios movies such as Thor and The Avengers. You're most welcome.
What's wrong with Friday?
As for Friday, it has long been considered unlucky. Jesus was crucified on a Friday before rising up again on Easter. In maritime circles, Friday was traditionally thought of as a bad day to embark on a voyage.
This wariness over Friday the 13th can been seen in popular culture.
For example, the popular Friday the 13th movie franchise, made up of 12 (no, not 13) films so far, chronicles fictional slasher Jason Voorhees' murderous rampages. The movies traumatised a whole generation into fearing men wearing hockey masks.
More recently in 2012, the Costa Concordia cruise ship ran aground off the western coast of Italy leading to 30 deaths. The tragedy occurred on Jan 13 - a Friday.
Real world impact
In Finland, every Friday the 13th is declared National Accident Day. On a day where everyone is paranoid with an overwhelming certainty that something bad is bound to happen, the country spends it raising awareness about safety in workplaces and in leisure times.
A Dutch study in 2008 revealed that there were fewer traffic accidents on Friday the 13th than on other normal Fridays, together with a drop in fire and theft.
However, such caution leads to noticeably slow economic activity. It is estimated to cost the United States between US$800 million and US$900 million in lost business on this day, as people will avoid activities such as getting on a plane for a business trip.
The double whammy
This round's Friday the 13th is special because it coincides with a full moon. This is quite a rare event, especially when you consider the probability of a Friday, a full moon and the 13th of the month all falling in the same 24 hours.
The last time this happened was at the start of the millennium in October 2000, and you will have to wait until August 2049 for the next time this happens.
There is a myth that the full moon drives people mad or transforms them into werewolves. I don't know about you, but I'm pretty psyched to watch a werewolf meet a black cat.
Friday the 13th traditions
There are some popular taboos that arise during this special day.
Do not walk under a ladder, or you will break the "holy trinity" it forms with the wall and the ground.
Black cats are believed to bring bad luck, and you're supposed to avoid them if you see one. Well I don't really get this one - it would probably hurt all the same if a white cat clawed your face.
Don't break any mirrors or you would have seven years of bad luck, because it is believed that the mirror captures a part of your soul, and cracking it means breaking your soul.
Remember to also avoid big surprises, such as birthday parties or wedding proposals, on Friday the 13th. Receiving sudden shocks on this day would turn your hair white overnight. You could be transformed into Storm from X-Men, without the cool powers or Halle Berry's good looks.
When you yawn, you're supposed to cover your mouth, so the devil will not take the opportunity to enter your body. I'm thinking this is just a matter of having good manners.
Fishermen believe that you should not call the salmon by name on Friday the 13th. Call it "the beast" or simply "the fish". For all you Harry Potter fans out there, the salmon basically becomes Voldemort on this day.
Lastly, do not burn egg shells or it could lead to your chicken not being able to lay eggs. I can't think of a reason why in the world anyone would be burning egg shells.
Thank God it isn't always Friday the 13th.