Okay! This is interesting
Came across this term, " Black Friday" in the context of Thanksgiving a couple of days ago. Could not understand as to why this phrase was associated with this day. Of course being a finance person, the first thought that occurs on hearing the term is a market collapse (like here). So, I was confused about the association.
Finally checked the term on wikipedia today. Accoding to the entry, the first known usage of the term is from 1965 Philadelphia
"Black Friday" is the name which the Philadelphia Police Department has given to the Friday following Thanksgiving Day. It is not a term of endearment to them. "Black Friday" officially opens the Christmas shopping season in center city, and it usually brings massive traffic jams and over-crowded sidewalks as the downtown stores are mobbed from opening to closing.
There are other interesting facts. Check them out here