What does Frannie say about her mother's rule regarding sugar and what does she do to break that rule? What are the consequences?

Frannie's mother doesn't allow them to have sugar if the weather's bad because it makes them wild with no way to run off the excess energy. On the way home from the rec center, Frannie and Sean split a Hershey bar. Frannie says that she feels as if she's going to bounce off the ceiling if it doesn't stop snowing so she can get outdoors.