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

Other days

brow

Brow Day
unicorn

Unicorn Day
cuddle up

Cuddle Up Day
blanket fort

Blanket Fort Day
lisp

Lisp Day
ruby

Ruby Day
bounce

Bounce Day
hoodie

Hoodie Day
gum

Gum Day
law

Law Day