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

Other days

mean girls

Mean Girls Day
prosecco

Prosecco Day
artists

Artists Day
ask out your crush

Ask Out Your Crush Day
first love

First Love Day
polyamory

Polyamory Day
pumpkin

Pumpkin Day
pampering

Pampering Day
brow

Brow Day
ruby

Ruby Day