"Maddy's heart hammered so hard against her ribs it threatened to break them."
This is a hyperbole because it's an exaggeration. Maddy's heart is not literally going to break her ribs. The author uses this figurative language to emphasize the intense emotions Maddy is feeling, likely fear or anxiety.
Here are other potential examples of hyperbole from *Savvy*:
* "He had a voice like a foghorn." This exaggerates the volume and loudness of the voice.
* "I could feel the heat of his anger singe my eyebrows." This exaggeration conveys the intensity of the person's anger.
Hyperbole is often used in literature to create a humorous or dramatic effect. It can also be used to emphasize the intensity of a character's feelings or the significance of an event.