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

Other days

cuddle up

Cuddle Up Day
kiss a ginger

Kiss A Ginger Day
bounce

Bounce Day
buddy

Buddy Day
self care

Self Care Day
gum

Gum Day
lash

Lash Day
my little pony

My Little Pony Day
coffee

Coffee Day
girl friend

Girl Friend Day