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

Other days

lisp

Lisp Day
bow tie

Bow Tie Day
aloxolt

Aloxolt Day
ruby

Ruby Day
bounce

Bounce Day
pick me

Pick Me Day
gallery

Gallery Day
nae nae

Nae Nae Day
slime

Slime Day
eat what you want

Eat What You Want Day