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

Other days

ride the wind

Ride The Wind Day
boy friend

Boy Friend Day
cat girl

Cat Girl Day
self care

Self Care Day
blanket fort

Blanket Fort Day
lisp

Lisp Day
boyfriend

Boyfriend Day
one

One Day
ponytail

Ponytail Day
boba

Boba Day