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

Other days

fiancee

Fiancee Day
ponytail

Ponytail Day
nae nae

Nae Nae Day
stud

Stud Day
self appreciation

Self Appreciation Day
lisp

Lisp Day
china

China Day
cuddle up

Cuddle Up Day
frozen yogurt

Frozen Yogurt Day
cursing

Cursing Day