Oops, it doesn't look like 'do a grouch a favor day' is a national day..

Other days

brow

Brow Day
cat girl

Cat Girl Day
fiancee

Fiancee Day
girl friend

Girl Friend Day
kale

Kale Day
kiss a ginger

Kiss A Ginger Day
prosecco

Prosecco Day
pick me

Pick Me Day
one

One Day
bubble bath

Bubble Bath Day