I blundered upon the technique when I was 21. I had just told my sister Nadine that she was miserable and unkind and that I didn't want anything to do with her anymore. She countered by leaving an unremitting stream of poisonous invective on my answering machine. At least the first message was. I didn't listen to the other 20 or so. Confounded by my answering machine's two-minute limitation, Nadine called and called and called again. When the calls stopped, I walked over to the machine and pressed Delete All. I was past the point where I cared what she said about me. If it meant I'd heard the last of her, would gladly let her have the last word.
I wouldn't hear from her for eight years.
Score! I would come to call this my "last word policy." The basic human need to have the last word dovetails perfectly with the John need to avoid basic humans. Giving assholes the last word costs me nothing, especially if I don't actually read/hear it, and it invariably provides peace. The other party becomes preoccupied with denying me the last word, and they leave me alone, lest they lose their status. It's bliss.