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

Other days

boy friend

Boy Friend Day
lisp

Lisp Day
blanket fort

Blanket Fort Day
get funky

Get Funky Day
singles

Singles Day
unicorn

Unicorn Day
artists

Artists Day
kiss a brunette

Kiss A Brunette Day
law

Law Day
slime

Slime Day