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

Other days

brow

Brow Day
one

One Day
kiss a brunette

Kiss A Brunette Day
singles

Singles Day
eat what you want

Eat What You Want Day
fiancee

Fiancee Day
tulip

Tulip Day
ormille

Ormille Day
first love

First Love Day
blanket fort

Blanket Fort Day