In little women, why does amy hint to her sisters that she needs extra money?

Amy needed to be accepted in her school's social circle. She explained to her sisters, Meg and Jo, that she needed extra money to buy pickled limes since it was fashionable at her school to buy them and share it with the other girls. Since she could not afford to get one, she was not allowed to have more until she took the turn providing pickled limes.