Although Mayella Ewell is nearly 20 years old, she has no friends, rarely associates with other people, and has the social graces of a child. Scout wonders if "she got good sense?" Mayella has been forced to serve as the female head of the Ewell household, taking care of her brothers and sisters as best she can. Her life is one of drudgery only made worse by the presence of her father, Bob. She has probably never been shown any real attention or respect aside from when Tom Robinson occasionally passes by. No one has ever called her "Miss Mayella" or "ma'am" before, so when Atticus addresses her in this manner, she mistakes it for sarcasm. She has already witnessed the hostile cross-examination between Atticus and Bob, and she must have been terrified as she awaits her turn, looking at Atticus "furiously." Atticus, a true Southern gentleman, treats Mayella as respectfully as he would any other person he might meet on the street, but having never been subjected to such a courtesy before, she believes he was "makin' fun o' me... I don't hafta take his sass." It is Judge Taylor who assures Mayella that it was only
"Mr. Finch's way... He's not trying to mock you, he's just trying to be polite." (Chapter 18)
As was mentioned in the previous post, Mayella Ewell was raised in an abusive home by an alcoholic father and was forced to care for her siblings by herself. Despite being nineteen years old, Mayella has no friends or social life. Scout even mentions during the trial that Mayella Ewell must have been the loneliest person in the world. When Mayella is on the witness stand, Atticus begins his cross-examination and refers to her as "ma'am." Mayella more than likely has never been called ma'am before and takes offense. After witnessing her father's controversial testimony, Mayella felt hostile towards Atticus before he even began questioning her. Mayella believes that Atticus is mocking her when he calls her "ma'am," but Judge Taylor assures her that was not Atticus' intention. After hearing about Mayella's upbringing, Scout realizes that Mayella has had a rough life and has probably never been treated with common courtesy outside of her interactions with Tom Robinson.