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

Other days

kale

Kale Day
cuddle up

Cuddle Up Day
get funky

Get Funky Day
my little pony

My Little Pony Day
pumpkin

Pumpkin Day
first love

First Love Day
stress awareness

Stress Awareness Day
buddy

Buddy Day
mean girls

Mean Girls Day
gum

Gum Day