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

Other days

coffee

Coffee Day
mean girls

Mean Girls Day
tell a fairytale

Tell A Fairytale Day
bonang

Bonang Day
bow tie

Bow Tie Day
stress awareness

Stress Awareness Day
ruby

Ruby Day
emoji

Emoji Day
nae nae

Nae Nae Day
kale

Kale Day