actually i would think it's the number 13 which is a bad number cause 12 actually signifies completeness like 12 months in a year, 12 apostles of jesus (christian tradition that says Judas was the 13th to sit down at the Last Supper), 12 hours of the clock, etc and there was even a superstitions tat if there's 13 people sitting on the same table, one of the person may die. for those who have watched or read the 'Da Vinci Code' may know that this superstitious was arose because it was the date that the knights templar were all arrest in Paris.
Here is an additional info which i copied off some random website:
The actual origin of the superstition, though, appears also to be a tale in Norse mythology. Friday is named for Frigga, the free-spirited goddess of love and fertility. When Norse and Germanic tribes converted to Christianity, Frigga was banished in shame to a mountaintop and labeled a witch. It was believed that every Friday, the spiteful goddess convened a meeting with eleven other witches, plus the devil — a gathering of thirteen — and plotted ill turns of fate for the coming week. For many centuries in Scandinavia, Friday was known as "Witches' Sabbath."
believe it or not, there's even a phobia for friday the 13th which is known as friggatriskaidekaphobia. I read it from an article that retailers will lose somewhere around $800 million today cause some people are so superstitious that they dare not leave the relative safety of their homes on Friday the 13th. Don laugh and think that there isn't such a phobia and it was a made up one...there's actually an estimates of between 17 to 21 million people suffering from friggatriskaidekaphobia.
so maybe, i should go and tell my bos today tat i can't go to work cause i'm having friggatriskaidekaphobia. A great reason to give... :) guess it's not a bad day afterall...since weekend is coming so who cares whether the friday is 13th or not? *inserts Party People song from 911 #retro #90s* look at the bright side, for us chinese, the number 13 is actually quite an auspicious number which is a homophonous to the sentence 'sure to give birth' in mandarin. so be optimistic in life and everyday will be as happy and joyful. *hugz*