Final answer:
Jessie thought it was 'crazy' that Bernice had been pretending to be someone else during her trip to the beach with the Moriartys.
Step-by-step explanation:
Jessie thought it was 'crazy' that Bernice had been pretending to be someone else during her trip to the beach with the Moriartys. Bernice followed Marjorie's advice and tried to impress the boys by acting differently and using Marjorie's conversation topics.
However, Bernice realizes later that it was she who made the decision to go along with it and feels a sense of rebellion.