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

Other days

lost sock memorial

Lost Sock Memorial Day

Me Day

kale

Kale Day

azonto is acceptable

Azonto Is Acceptable Day

slime

Slime Day

blanket fort

Blanket Fort Day

fiancee

Fiancee Day

stress awareness

Stress Awareness Day

my little pony

My Little Pony Day

pick me

Pick Me Day