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

Other days

china

China Day
mean girls

Mean Girls Day
artists

Artists Day
one

One Day
lumpy rug

Lumpy Rug Day
eat what you want

Eat What You Want Day
gum

Gum Day
offer

Offer Day
pick me

Pick Me Day
ponytail

Ponytail Day