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

Other days

boyfriend

Boyfriend Day
self appreciation

Self Appreciation Day
lisp

Lisp Day
china

China Day
boy friend

Boy Friend Day
my little pony

My Little Pony Day
lash

Lash Day
camera

Camera Day
azonto is acceptable

Azonto Is Acceptable Day
self care

Self Care Day