Superstitions-----bad luck

1. Friday the 13th
If you're not scared of Friday the 13th, you should be scared of the word used to describe those who are: friggatriskaidekaphobics(An alternative,though just as tongue--twisty,word for the fear is "paraskevidekatriaphobia")

For a superstition, the fear of Friday the 13th seems fairly new,dating back to the late 1800s.  Friday has long been considered an unlucky day(according to Christian tradition,Jesus died on a Friday),and 13 has a long history as an unlucky number.

2.No umbrellas inside
...And not just because you'll poke someone's eye out.  Opening an umbrellas indoor is supposed to bring bad luck,though the origins of this belief are murky.  Legends abound,from a story of an ancient Roman woman who happened to have opened her umbrella moments before her house collapsed,to the tale of a British prince who accepted two umbrellas from a visiting king and died within months.  Like the "don't walk under a ladder" superstition,this seems to be a case of a myth arising to keep people from doing something that is slightly dangerous in the first place.

3.666
Three sixes in a row give some people the chills. It's a superstition that harks back to the Bible.  In the book of Revelation,666 is given as the number of the "beast", and is often interpreted as the mark of Satan and a sign of the end times.  According to state University of New York at Buffalo anthropologist Philips Stevens, the writer of Revelation was writing to persecuted Christian in code,so the number and names in the book are contemporary references.  Three sixes in a row is probably the numeric equivalent of the Hebrew letter for the first-century Roman Emperor Nero.

4.Black cats crossing your path
As companion animals for humans for thousands of years, cats play all sorts of mythological roles.  In ancient Egypt, cats were revered; today. Americans collectively keep more than 81 millon cats as pets.

So why keeps black cat out of your path? Most likely, this superstition.arises from old beliefs in witches and their animal familiars, which were often said to the form of domestic animals like cats.

5.Don't walk under that ladder
Frankly, this superstition is pretty practical.  Who wants to be responsible for stumbling and knocking a carpenter off his perch?  But one theory that this superstition arises from a Christian belief in the Holy Trinity:  Since a ladder leaning against a wall forms a triangle, "breaking" that triangle was blasphemous.

Then again, another popular theory is fear of walking under a ladder has to do with its resemblance to a medieval gallows.  We're sticking with the safety-first explanation for this one.