Oops, it doesn't look like 'ha ha holiday ha ha holiday heeeeeeeeeeeee day' is a national day..

Other days

slime

Slime Day
cuddle up

Cuddle Up Day
cursing

Cursing Day
carpenters

Carpenters Day
boy friend

Boy Friend Day
eat what you want

Eat What You Want Day
singles

Singles Day
me

Me Day
prescription drug take back

Prescription Drug Take Back Day
ruby

Ruby Day