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

Other days

brow

Brow Day
pumpkin

Pumpkin Day
healing

Healing Day
blanket fort

Blanket Fort Day
eat what you want

Eat What You Want Day
law

Law Day
martini

Martini Day
coffee

Coffee Day
artists

Artists Day
self appreciation

Self Appreciation Day