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

Other days

bow tie

Bow Tie Day
self care

Self Care Day
get funky

Get Funky Day
blanket fort

Blanket Fort Day
law

Law Day
boba

Boba Day
stud

Stud Day
cursing

Cursing Day
buddy

Buddy Day
believe

Believe Day