Oops, it doesn't look like 'Text Back Slow day' is a national day..

Other days

Chocolate Milkshake Day

Cuddle Up Day

Hot Chocolate Day

African Immigrant And Refugee Hiv And Hep Awareness Day

Martini Day

Embarrass Your Best Friend Day

Azonto Is Acceptable Day

Aloxolt Day

Lost Sock Memorial Day

My Little Pony Day