MadHatterDay is a holiday in October. It fills the need for a second crazy day in the year, almost exactly half a year from April Fools' Day. The real spirit of MadHatterDay is turnabout: The nonsense we usually have to pretend is sane can be called madness for one day in the year; the superficially crazy things that really make sense can be called sane on MadHatterDay.
MadHatterDay is 10/6. Just a FYI