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

Other days

one

One Day
kale

Kale Day
lash

Lash Day
nail polish

Nail Polish Day
hoodie

Hoodie Day
frozen yogurt

Frozen Yogurt Day
cursing

Cursing Day
pick me

Pick Me Day
stud

Stud Day
pampering

Pampering Day