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

Other days

book

Book Day
lisp

Lisp Day
ride the wind

Ride The Wind Day
china

China Day
nail polish

Nail Polish Day
self care

Self Care Day
lash

Lash Day
hannah

Hannah Day
ormille

Ormille Day
tell a fairytale

Tell A Fairytale Day