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

Other days

offer

Offer Day
nail polish

Nail Polish Day
comfy

Comfy Day
boy friend

Boy Friend Day
kiss a ginger

Kiss A Ginger Day
reading

Reading Day
martini

Martini Day
my little pony

My Little Pony Day
promposal

Promposal Day
kale

Kale Day