Oops, it doesn't look like 'dress like blake shelton day' is a national day..

Other days

law

Law Day
one

One Day
artists

Artists Day
gum

Gum Day
martini

Martini Day
bow tie

Bow Tie Day
self care

Self Care Day
lash

Lash Day
tulip

Tulip Day
kiss a brunette

Kiss A Brunette Day