This is one of the best early episodes. It's a standalone story, about a boy who makes a mean joke to hurt his sister. He makes her think the dentist will pull all of her teeth, so she is absolutely terrified. The dentist and the sister give the boy a taste of his own medicine, so that he learns what it does.
The dentist said it well: Emily and I are friends, and you made Emily distrust me, and that hurts.
5/5