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

Other days

buddy

Buddy Day
coffee

Coffee Day
pampering

Pampering Day
hot chocolate

Hot Chocolate Day
get funky

Get Funky Day
nae nae

Nae Nae Day
lisp

Lisp Day
martini

Martini Day
bubble bath

Bubble Bath Day
boba

Boba Day