Oops, it doesn't look like 'fool day' is a national day..

Other days

fiancee

Fiancee Day
bounce

Bounce Day
my little pony

My Little Pony Day
carpenters

Carpenters Day
ormille

Ormille Day
one

One Day
first love

First Love Day
self care

Self Care Day
stress awareness

Stress Awareness Day
healing

Healing Day