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

Other days

slime

Slime Day
eat what you want

Eat What You Want Day
mean girls

Mean Girls Day
boba

Boba Day
offer

Offer Day
law

Law Day
singles

Singles Day
coffee

Coffee Day
nae nae

Nae Nae Day
my little pony

My Little Pony Day