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

Other days

aloxolt

Aloxolt Day
singles

Singles Day
camera

Camera Day
boyfriend

Boyfriend Day
polyamory

Polyamory Day
comfy

Comfy Day
boy friend

Boy Friend Day
girl friend

Girl Friend Day
unicorn

Unicorn Day
cuddle up

Cuddle Up Day