my dad beats me with jumper cables

I live with my dad and my 9 year old daughter. I sometimes go to the gym at night and tell my daughter to brush her teeth while I'm gone. When I get back she shows me a video on our tablet of her brushing her teeth as proof. A few days ago I realized that her hairstyle was slightly different in the video, and I figured out that she had simply prerecorded herself brushing her teeth in several different outfits. While I was fairly impressed at this, I kept a straight face and explained to her that when I was a kid, grandpa would beat me savagely with a set of jumper cables whenever I didn't brush my teeth. Since then she's been brushing several times a day on her own.