In North America, the number 13 is bad luck.
Elevators do not have a 13th floor.
Some people also believe that the day "Friday the 13th" is bad luck (for example, March 13).
Black cats are also bad luck.
This blog is mainly to explain a different English language expression every day. Sometimes I post other stuff. I also have a YouTube channel which is mostly about computer software: https://www.youtube.com/englishspacedog
