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

Other days

cursing

Cursing Day
comfy

Comfy Day
kale

Kale Day
gum

Gum Day
special education

Special Education Day
boy friend

Boy Friend Day
ponytail

Ponytail Day
kiss a brunette

Kiss A Brunette Day
artists

Artists Day
bounce

Bounce Day