Oops, it doesn't look like 'Age Of Ultron Viewing day' is a national day..

Other days

brow

Brow Day
my little pony

My Little Pony Day
mean girls

Mean Girls Day
buddy

Buddy Day
ruby

Ruby Day
slime

Slime Day
book

Book Day
hoodie

Hoodie Day
ride the wind

Ride The Wind Day
ormille

Ormille Day