What does scout mean when he says then jem rose and broke the remaining code of their childhood

When Jem and Scout discover Dill hiding under Scout's bed. Dill tells a long story about being locked and chained in a basement and escaping with a traveling animal show. Then, he tells the real story of how he stole money from his mother's purse, and walked and hitched his way from the train station to the Finch house. Dill is very hungry and Scout gets him some cold cornbread to eat while mentally noting that Dill is now "home." Jem says that Dill should let his mother know where he is and goes to report the situation to Atticus. Scout remarks that by taking this action, Jem "broke the remaining code of our childhood".