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

Other days

artists

Artists Day
fiancee

Fiancee Day
hot chocolate

Hot Chocolate Day
slime

Slime Day
offer

Offer Day
boy friend

Boy Friend Day
kiss a ginger

Kiss A Ginger Day
law

Law Day
girl friend

Girl Friend Day
cuddle up

Cuddle Up Day