Thank you to an anonymous emailer for this scenario:
"What would Nancy Drew do about mean girls in school?"
Well, In The Secret of the Old Clock, Nancy frequently runs into the Topham girls (Isabel and Ada) who are known for being the "mean girls" in town. According to this book, the Topham sisters became jealous of Nancy's popularity in school. Even though those girls are very rude to Nancy, she always tries to be very polite to them no matter what they say.