the carrot and the stick

[yflyn]

Yesterday at the supermarket, Bao was acting up while in her stroller. She managed to wriggle her bottom low enough on the seat so that her feet dragged on the floor or on the wheels, making it difficult for me to push the stroller and sometimes even tripping me up. The kids had already been told that they would get a Kinder egg if they were good, so I stopped and reminded her about this.

Me: You want a chocolate egg, right? You have to be good and sit up properly so that I can get all the shopping done.
Bao: No.
Me: You don't want a chocolate egg?
Bao: No.

At the cash register I bought two eggs anyway, just to see if she would smarten up and accept the bribe shape up. She didn't, and kept dragging her feet all the way to the car. After dinner The Bun claimed his treat and ate it at the dinner table, in front of his sister. J had reminded me beforehand to stay firm and not give her an egg she didn't deserve.

Bao, wistfully watching her brother devour chocolate: I was naughty. I didn't listen. I have no egg.
Me: If you're good the next time you can have an egg. Will you be good?
Bao, singsong: No thank you!

I had no response to that because I had to turn away before she could see me laugh.

What do you do when neither the carrot nor the stick will work?