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

Other days

unicorn

Unicorn Day
hoodie

Hoodie Day
slime

Slime Day
boy friend

Boy Friend Day
gum

Gum Day
girl friend

Girl Friend Day
booty pic

Booty Pic Day
carpenters

Carpenters Day
ormille

Ormille Day
singles

Singles Day