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

Other days

stud

Stud Day
first love

First Love Day
ponytail

Ponytail Day
pick me

Pick Me Day
tell a fairytale

Tell A Fairytale Day
book

Book Day
self care

Self Care Day
gum

Gum Day
ruby

Ruby Day
bounce

Bounce Day