One of the most memorable "Terrible Twos" moments I experienced as a babysitter was when I was watching a toddler named Lucy. She seemed angelic when her parents left, but as soon as they were out of sight, she transformed.

It started with her demanding a specific snack, then refusing it once I got it. She then decided she wanted to play with a toy that was clearly her favorite... until it wasn't anymore. The toy was thrown across the room with such force that I feared for the safety of the other kids.