Sassy Little Thing

So when Katie does something she knows she's not supposed to, I sternly say "No" and shake my head. If she is grabbing at something, etc, I will hold her arm/hand to help her get the message. Well, just today, she has started looking at me, doing said action she is not supposed to, looking at me, and shaking her head. She then proceeds to reach over and grab my arm. Oh dear....