In this scene, Penny bullies Sherman by calling him a dog. It's a great way to teach what bullying is and how it looks and feels to the person being bullied.
Tara bullies Chrissa by bumping into her, then sticking her with a pen when no one else is watching. Chrissa is upset, and ends up going to the bathroom to inspect the damage. While in there, Tara takes the envelope she was supposed to bring to the office and does it herself to embarrass Chrissa.
Key and Peele perform a skit that brings attention to the deeper reasons that kids bully each other. Peele bullies Key while he is reading a book and explains on a deep level why he makes each of his remarks.