because black means sad and it was on a Saturday .
Black Saturday - Lebanon - happened on 1975-12-06.
7,500 people were left homeless after the Black Saturday bushfires.
15663 hectares of land was destroyed during black Saturday.
black or bluish black
Black Saturday sometimes is used to refer to Holy Saturday, the day before Easter Sunday. It is rarely used, at least, in the United States.
Saturday
Bush fire, really big ones wild fire, firestorm, hellfire, the biggest, will be named after the that day with the prefix "Black" ie Black Saturday. unless it coming straight at you then you call it every name under the sun.
nothing
NOTHING
No.
They don't, Easter Saturday is the Saturday following Easter. Holy Saturday is the day before Easter.