Oops, it doesn't look like 'mourningflag will fly at half mast day' is a national day..

Other days

Bonang Day

Reading Day

Tulip Day

My Little Pony Day

Bow Tie Day

Coffee Day

Appreciate Yaself A Lil Extra Day

Slime Day

Lost Sock Memorial Day

African Immigrant And Refugee Hiv And Hep Awareness Day