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

Other days

singles

Singles Day
polyamory

Polyamory Day
bow tie

Bow Tie Day
kale

Kale Day
cursing

Cursing Day
eat what you want

Eat What You Want Day
cuddle up

Cuddle Up Day
self care

Self Care Day
one

One Day
kiss a brunette

Kiss A Brunette Day