Oops, it doesn't look like 'no rivals day' is a national day..

Other days

boyfriend

Boyfriend Day
bubble bath

Bubble Bath Day
prosecco

Prosecco Day
hannah

Hannah Day
cuddle up

Cuddle Up Day
girl friend

Girl Friend Day
nae nae

Nae Nae Day
mean girls

Mean Girls Day
nail polish

Nail Polish Day
kale

Kale Day