What does DBNT mean or stand for ?

DBNT also used as- Don’t bother. It could be understood  as both a sarcastic phrase as well as a selfless statement. For example- Jessica’s grandmother ask her “if you are going to a store then please pick up some fruits , else don’t bother”.

Lucy yelled at her boyfriend James on the phone saying “you forgot to call me last night, Don’t bother next time”.