“See there?” Jem was scowling triumphantly. “Nothin’ to it. I swear, Scout, sometimes you act so much like a girl it’s mortifyin’.”
There was more to it than he knew, but I decided not to tell him.

– Harper Lee

To Kill a Mockingbird, Chapter 4. Jem attacks Scout’s gender and insults her about acting like a girl whenever he feels she challenges his manhood. In this instance the tire he was pushing her in rolls into Radley’s yard and she makes him retrieve it. What she didn’t tell him was that she heard laughter coming from the Radley home. Boo is obviously inside watching them play, this foreshadows the important role he will have in the children’s lives.