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

Other days

gum

Gum Day
my little pony

My Little Pony Day
lisp

Lisp Day
book

Book Day
boy friend

Boy Friend Day
singles

Singles Day
hiv awareness

Hiv Awareness Day
girl friend

Girl Friend Day
tulip

Tulip Day
kiss a brunette

Kiss A Brunette Day