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

Other days

lisp

Lisp Day
get funky

Get Funky Day
self care

Self Care Day
ruby

Ruby Day
blanket fort

Blanket Fort Day
hannah

Hannah Day
nae nae

Nae Nae Day
lost sock memorial

Lost Sock Memorial Day
pick me

Pick Me Day
slime

Slime Day