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

Other days

pampering

Pampering Day
camera

Camera Day
law

Law Day
get funky

Get Funky Day
donate your hair

Donate Your Hair Day
ruby

Ruby Day
eat what you want

Eat What You Want Day
lash

Lash Day
lumpy rug

Lumpy Rug Day
china

China Day