"They'd be right, because you're absolutely not one." They'd be wrong because he absolutely is, but she keeps that information to herself. While John fills up the kettle, he may hear her trying to play quietly, but whatever she's up to is just as frustrating as it is amusing, and she's doing a lot of talking despite the fact that a good three-quarters of her voice is gone.

"Who the fuck---? OH, MY GOD! STOP HACKING ME! I JUST WANT TO PLAY! I'm gonna find you and you're dea---THERE YOU ARE!"

This is typical Charlie playing video games. She doesn't actually get mad. She just gets goofy, and a bit petty. So by the time John comes back out, he may get a glimpse of Charlie using the games character to steal a car and run down whoever it was that was hacking her characters phone, knocking the other player off a cliff and into a lake.

"Asshole."