Growing up, we referred to Friday the 13th as Black Friday. It wasn’t until last November that I found out that Black Friday is also the name for the big shopping day immediately following Thanksgiving in the USA, and apparently the Friday just before Christmas in the UK (a big party day). It seems that my usage is non-standard at best (that is, pretty much unknown). Black Friday is also the name that has been given to numerous tragic events, as it seems like bad things happen fairly often on Fridays.
In some places, especially the United States and Commonwealth countries, today is especially unlucky because it is the combination of two unlucky things: Friday, and the number 13. The superstition causes many people to pay extra attention to staying safe, not letting black cats cross their paths, and not walking under ladders (other supposedly unlucky occurrences). Some people are so paralysed by a fear of this day that they can’t leave their houses and some can’t do anything on these days. The phobia is known as paraskavedekatriaphobia, or friggatriskaidekaphobia, which I think is an excellent word to try to say.
Interestingly enough, though Friday and 13 have individually been seen as unlucky for centuries, the combination has only been seen as a particularly unlucky day for the last 100 or so years.
In Greece and in certain Spanish-speaking countries (Mexico, Spain, and some parts of Latin America), it’s not the Friday that should be feared, but Tuesday the 13th. Tuesday is considered the worst day of the week, and why not, as you haven’t even reached Wednesday (the ‘hump’ day) yet. As a result of this, the horror film franchise Friday the 13th, although released in Spain as Viernes 13 (Friday the 13th), was released in Argentina as Martes 13, or Tuesday the 13th.