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

Other days

law

Law Day
lumpy rug

Lumpy Rug Day
china

China Day
ruby

Ruby Day
boyfriend

Boyfriend Day
get funky

Get Funky Day
unicorn

Unicorn Day
gum

Gum Day
latina equal pay

Latina Equal Pay Day
cuddle up

Cuddle Up Day