Some very funny methods!
Wonderful technique Hannah's Mom!
The one I have used and read about alot is to be "unable to hear" certain tones of voice. Works best when it's not a reply to something you said.
As in: "I'm sorry, dear daughter/son, I cannot understand you when you talk that way. What did you really mean to say?" in a <I>very </I>calm rational voice.
My own daughter has mostly mastered her Sassy tones now. She was naturally gifted with Sass from birth, and it caused her problems in all of her relationships.
Another time, when we were all on a trip, and had a captive audience so to speak; Dear Dad and I launched into a conversation in which we were disrespectful, and sassy, using certain tones of voice. Our children were absolutely shocked, and fascinated - but very upset! It grabbed their attention so well we were really able to get them to understand what they sound like, and how they treat each other. My husband and I get along so well, they have never heard us talk to each other that way except in a teasing manner, so it was very effective.