Triskaidekaphobia

Don't bother yourself if you can't read the title. I just did it once and won't do it ever again. But if you're wondering what it is, it is the fear of number 13. In most cultures 13 is assumed to be a bad number. (perhaps I have to change all the 13's to 12+1)
A reason that people consider it a bad number is that it is more than 12 which is a number commonly used and sometimes a sacred number. Besides, if you divide 13 objects into many groups, there is always one left alone which should be kind of scary!! Actually, I am a little suspicious about all prime numbers.
Some people consider the failure of Apollo 13's mission as an example that 13 is a cursed number. Even in Formula 1 there is no car with the number 13. The number has been removed after two drivers were killed in crashes both having the number 13.
Anyway, the fear of the Friday the 13th is called paraskavedekatriaphobia which is so hard to read that makes it less scary.