Oops, it doesn't look like 'park and on what day' is a national day..

Other days

lisp

Lisp Day
slime

Slime Day
comfy

Comfy Day
frozen yogurt

Frozen Yogurt Day
ruby

Ruby Day
artists

Artists Day
one

One Day
camera

Camera Day
tell a fairytale

Tell A Fairytale Day
nae nae

Nae Nae Day