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

Other days

law

Law Day
bonang

Bonang Day
get funky

Get Funky Day
gum

Gum Day
bow tie

Bow Tie Day
self care

Self Care Day
kiss a brunette

Kiss A Brunette Day
girl friend

Girl Friend Day
book

Book Day
offer

Offer Day