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

Other days

polyamory

Polyamory Day
nae nae

Nae Nae Day
eat what you want

Eat What You Want Day
one

One Day
first love

First Love Day
china

China Day
bubble bath

Bubble Bath Day
pick me

Pick Me Day
brow

Brow Day
law

Law Day