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

Other days

polyamory

Polyamory Day
boy friend

Boy Friend Day
bow tie

Bow Tie Day
me

Me Day
one

One Day
stress awareness

Stress Awareness Day
comfy

Comfy Day
eat what you want

Eat What You Want Day
cat girl

Cat Girl Day
ruby

Ruby Day