Oops, it doesn't look like 'wash your car day' is a national day..

Other days

lash

Lash Day
cursing

Cursing Day
youth

Youth Day
first love

First Love Day
one

One Day
gum

Gum Day
kiss a ginger

Kiss A Ginger Day
tulip

Tulip Day
blanket fort

Blanket Fort Day
prosecco

Prosecco Day