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

Other days

martini

Martini Day
singles

Singles Day
one

One Day
gum

Gum Day
tell a fairytale

Tell A Fairytale Day
tulip

Tulip Day
unicorn

Unicorn Day
promposal

Promposal Day
latina equal pay

Latina Equal Pay Day
self care

Self Care Day