Oops, it doesn't look like 'assembly on same day' is a national day..

Other days

buddy

Buddy Day
artists

Artists Day
ruby

Ruby Day
get funky

Get Funky Day
china

China Day
kiss a brunette

Kiss A Brunette Day
blanket fort

Blanket Fort Day
fiancee

Fiancee Day
pick me

Pick Me Day
unicorn

Unicorn Day