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

Other days

polyamory

Polyamory Day
self care

Self Care Day
cat girl

Cat Girl Day
offer

Offer Day
kale

Kale Day
ruby

Ruby Day
pick me

Pick Me Day
ponytail

Ponytail Day
mean girls

Mean Girls Day
girl friend

Girl Friend Day