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

Other days

one

One Day
girl friend

Girl Friend Day
get funky

Get Funky Day
book

Book Day
boy friend

Boy Friend Day
kiss a brunette

Kiss A Brunette Day
believe

Believe Day
lash

Lash Day
my little pony

My Little Pony Day
martini

Martini Day