Peter wanted a chocolate. He was sure of that. He also wanted Mom to stop talking to the man behind the counter. He wanted her to get them to school so he could play with his school mates.
If he had a chocolate and they didn't, he'd be cool at school. Perhaps if he went and got one he could sneak it out and no one would know? Mom said not to steal, but what did she know? Parents were lame.
These thoughts swirled in his head, and he wasn't sure if he should listen to his conscience or his brain.