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

Other days

donate your hair

Donate Your Hair Day
boy friend

Boy Friend Day
fiancee

Fiancee Day
tulip

Tulip Day
polyamory

Polyamory Day
ormille

Ormille Day
unicorn

Unicorn Day
bow tie

Bow Tie Day
youth

Youth Day
camera

Camera Day