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

Other days

stud

Stud Day
martini

Martini Day
cursing

Cursing Day
ponytail

Ponytail Day
bow tie

Bow Tie Day
lost sock memorial

Lost Sock Memorial Day
one

One Day
gum

Gum Day
law

Law Day
ask out your crush

Ask Out Your Crush Day