"It's not fair!"

I didn't expect to hear these words so soon, especially from my just-barely-three-year-old. Kedrick got a marshmallow for using the potty (woohoo Kedrick!). Victor wanted one too. I told him he could have one when he went poo-poo in the potty. He screamed, "I don't want to use the potty! I want a marshmallow! It's not fair!"

Where did he learn that?