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

Other days

stud

Stud Day
china

China Day
fiancee

Fiancee Day
kiss a ginger

Kiss A Ginger Day
slime

Slime Day
blanket fort

Blanket Fort Day
law

Law Day
boy friend

Boy Friend Day
gum

Gum Day
lumpy rug

Lumpy Rug Day