Why does sal tell phoeb's story

Sal is telling the story to her Grandparents since her Grandmother asked for Sal to entertain her. Sal could not think of what to say or tell her grandparents so she asked for an example. Grams said, “Well then, what about your friends? You got any tale to tell about them?” And Phoebe Winterbottom came to her mind. For short, Sal told the story of Phoebe since it was instantly the first thing that came to Sal’s mind.