How does the author use foreshadowing in A Frolic of His Own?

While Christina and Harry are having dinner, she recalls the morning's phone conversation with Oscar, who is convinced that Mudpye's poking him in the chest to make a point has broken his sternum. He also insists that Mudpye's slapping him on the shoulder has cracked his scapular. Their conversation foreshadows a lawsuit, as under the law, poking someone without consent constitutes battery