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

Other days

self appreciation

Self Appreciation Day
ruby

Ruby Day
lash

Lash Day
china

China Day
ponytail

Ponytail Day
tulip

Tulip Day
hannah

Hannah Day
first love

First Love Day
chocolate milkshake

Chocolate Milkshake Day
camera

Camera Day