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

Other days

lisp

Lisp Day
pick me

Pick Me Day
singles

Singles Day
boy friend

Boy Friend Day
gum

Gum Day
coffee

Coffee Day
donate your hair

Donate Your Hair Day
ride the wind

Ride The Wind Day
cuddle up

Cuddle Up Day
brow

Brow Day