Man, we have started that big time around here. All my efforts to remain calm and cool...to try to use some Love & Logic stuff like being sure to present choices just gets me no where! "No, I want _____." and "Mummy, you need to _____." are hatefully coming out of her mouth all the time.
I often say what Keri does, get that mom tone of voice and tell her "no ma'am you don't speak that way to ___" but I still feel like we are getting way more than we should. I'm going to take another Love & Logic class to try to drill it into my head a little better as I know me keeping my cool and changing the way I say things is the best way to get the kind of behavior I want. And I also see what Melissa is saying about having a no-tolerance policy on it. Ay! Somedays I feel like we have a no-tolerance policy on everything!
Good luck to you Finn! If you find anything that works, let me know.
BTW, I have already threatened duct tape

but she wrote me off when she noticed that "I'll hang you up by your toenails" twinkle in my eye.