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

Other days

offer

Offer Day
comfy

Comfy Day
eat what you want

Eat What You Want Day
china

China Day
get funky

Get Funky Day
hoodie

Hoodie Day
slime

Slime Day
martini

Martini Day
law

Law Day
girl friend

Girl Friend Day