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

Other days

ponytail

Ponytail Day
cursing

Cursing Day
cat girl

Cat Girl Day
gum

Gum Day
nae nae

Nae Nae Day
boy friend

Boy Friend Day
ride the wind

Ride The Wind Day
lumpy rug

Lumpy Rug Day
prosecco

Prosecco Day
stud

Stud Day