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

Other days

pampering

Pampering Day
azonto is acceptable

Azonto Is Acceptable Day
nae nae

Nae Nae Day
gum

Gum Day
kale

Kale Day
mean girls

Mean Girls Day
cuddle up

Cuddle Up Day
stud

Stud Day
blanket fort

Blanket Fort Day
martini

Martini Day