My cousin's daughter is 7. I've always had a little game with her where I pick her up and spin her around gently. Every kid I've known LOVES this. She was enjoying it as usual and then suddenly she says to me "You need help. You should see a doctor." She was already being sassy to a few other people so I told her "Okay, I will. Your mother is a doctor, right? I'll tell her all about how you've been acting up." "I'm sorry, please don't tell mom." "No more attitude, okay?"
That worked. \o/