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

Other days

slime

Slime Day
youth

Youth Day
lash

Lash Day
boba

Boba Day
bounce

Bounce Day
donate your hair

Donate Your Hair Day
fiancee

Fiancee Day
blanket fort

Blanket Fort Day
tell a fairytale

Tell A Fairytale Day
ride the wind

Ride The Wind Day