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

Other days

artists

Artists Day
my little pony

My Little Pony Day
bounce

Bounce Day
first love

First Love Day
hoodie

Hoodie Day
cursing

Cursing Day
get funky

Get Funky Day
tulip

Tulip Day
reading

Reading Day
nail polish

Nail Polish Day