When does playing the dozens go to far?

Everyone at some point has probably played the game refereed to as 'playing the dozens' also know as trash talking. This is game where you are saying mean things back and forth with a person until someone says something that is the most hurtful and the game is over. I have personally never seen this game end in a pleasant way and most of the people involved walk away with hurt feelings and many end up never talking to each other again. So I pose the question have you ever played this game and it end up well or if you haven't do you think it's possible for it to end in such a way where no one walks away hurt?