had traditionally been an occasion for popular and often raucous celebrations, regardless of the locally prevalent political or religious establishment.
As Europe became Christianized the pagan holidays lost their religious character and either changed into popular secular celebrations, as with May Day, or were replaced by new Christian holidays as with Christmas, Easter, and All Saint's Day. In the twentieth century, many neopagans began reconstructing the old traditions and celebrating May Day as a pagan religious festival again. Wikipedia.
Friday can call for a party planned or one dropped from a hat.