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

Other days

china

China Day
camera

Camera Day
law

Law Day
ruby

Ruby Day
believe

Believe Day
boy friend

Boy Friend Day
kiss a ginger

Kiss A Ginger Day
nae nae

Nae Nae Day
azonto is acceptable

Azonto Is Acceptable Day
aloxolt

Aloxolt Day