Mulligan Day was named after the golfer David Mulligan who made a mistake during a game and retook his shot.
Since then, to ‘call a mulligan’ means a second chance to perform an action.
The term ‘mulligan’ is not only used in golf, but also in several other sports and games.
There is even a mulligan stew where the stew is made with left overs.
So in short, this is a day where you have an
excuse reason to take a second chance on something.