Sleepie, "quacking" is a way for loved ones to think of it when an actively addicted person is talking in service of their addiction. E.g. promising to change, or telling lies to hide the problem, or blaming the other person for their problem. I don't know where the duck/quacking metaphor came from specifically. But for loved ones to recognize quacking is similar to an addict needing to recognize AV. It's training ourselves not to listen when the addiction is talking, whether it's inside our head or through someone else's mouth!