Oops, it doesn't look like 'be an ass day' is a national day..

Other days

ruby

Ruby Day
aloxolt

Aloxolt Day
kiss a ginger

Kiss A Ginger Day
first love

First Love Day
kale

Kale Day
pumpkin

Pumpkin Day
reading

Reading Day
camera

Camera Day
cat girl

Cat Girl Day
brow

Brow Day