Stuart Vyse, a psychology professor at Connecticut College, told USA Today that 13 guests are believed to have attended the Last Supper the night before Jesus was killed. The disciple who betrayed Jesus is believed to have been the 13th guest.
You're not more likely to go to the hospital.
A study published in World Journal of Surgery in 2011 found that there's no link between Friday the 13th and an increase of blood loss or the frequency of emergency room visits on that day.
"Our data indicate that such beliefs are myths far beyond reality," the study said.
Some people have a fear of the actual day when Friday falls on a month's 13th day.
They're called paraskevidekatriaphobics.
Other people choose to get married on the day.
The Viva Las Vegas wedding chapel offers three different packages on Friday the 13th: Zombie, vampire and "Rocky Horror"-themed ceremonies.
There are two Friday the 13ths this year.
April 13 and July 13 are on Friday this year. Last year, Jan. 13 and Oct. 13 fell on a Friday.
Outer space is affected by Friday the 13th too.
According to NASA, a large asteroid will fly close enough to the Earth to be visible without a telescope in Africa, Europe and Asia on Friday, April 13, 2029.
Singer Taylor Swift has a special connection to the number 13.
"I was born on the 13th. I turned 13 on Friday the 13th. My first album went gold in 13 weeks. My first No. 1 song had a 13-second intro," the singer told MTV in a 2009 interview.