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

Other days

blanket fort

Blanket Fort Day
tulip

Tulip Day
ride the wind

Ride The Wind Day
china

China Day
first love

First Love Day
polyamory

Polyamory Day
nail polish

Nail Polish Day
tell a fairytale

Tell A Fairytale Day
stud

Stud Day
nae nae

Nae Nae Day