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

Other days

carpenters

Carpenters Day
pick me

Pick Me Day
cat girl

Cat Girl Day
brow

Brow Day
offer

Offer Day
boba

Boba Day
ride the wind

Ride The Wind Day
mean girls

Mean Girls Day
chocolate milkshake

Chocolate Milkshake Day
ruby

Ruby Day