It's wrong to deceive your children.
Julie's son needs to visit the dentist, but he hates going to the dentist.
Julie wants to drive her son to the dentist.
Julie tells her son that he must go to the dentist even though he doesn't want to, and they drive there.
Julie tells her son that they are driving to get ice-cream but actually takes him to the dentist's office.
Julie's son learns that sometimes unpleasant things have to be faced for his own good.
Julie's son is horrified at her lie and develops trust issues with her after this.