Answer:
Calpurnia smacks Scout as a punishment for making rude comments about Walter's eating habits at the dinner table.
Step-by-step explanation:
In Chapter 3, Jem invites Walter Cunningham Jr. over to eat dinner with his family, and Walter proceeds to pour syrup all over his meal. Scout is disgusted at Walter's eating habits and rudely comments on the fact that he is pouring syrup all over his meat and vegetables. Scout embarrasses Walter by asking "what the sam hill" he is doing. Calpurnia then requests Scout's presence in the kitchen and proceeds to reprimand Scout for her rude remarks. Calpurnia chastises Scout for not treating Walter with respect and tells her to stop acting so "high and mighty!". Calpurnia also makes Scout finish her meal in the kitchen and smacks her while she is walking into the dining room to retrieve her plate. While Scout is eating alone in the kitchen, she contemplates on how she will get revenge on Calpurnia for punishing her.