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

Other days

stud

Stud Day
kiss a brunette

Kiss A Brunette Day
ride the wind

Ride The Wind Day
ormille

Ormille Day
lisp

Lisp Day
bounce

Bounce Day
china

China Day
one

One Day
self appreciation

Self Appreciation Day
gum

Gum Day