What is the point of the "challenge to be kind" option?

I've done it on a few sims now, and something I noticed is that when you first call her over to start the challenge, she always digs in your trash and leaves a pile on your lot. After you're done, you can challenge her to be kind, and she will take out the trash for you (if you have any on the lot). I thought that was cute. Maybe that's what it's supposed to do, that's all I seem to have noticed so far.