In Ch. 24 Aunt Alexandra is hosting a meeting of the Missionary Circle and Atticus has been nice enough to supply the food for the meeting.

During the meeting the conversation moves from the  missionaries in their church who are trying to convert an African tribe to Christianity to the topic of the black help there in Macomb. Miss Merriweather says that she doesn't know why some black people are so cranky because Jesus was never cranky. She then goes on to say there are some white folks in town, who she won't name but she is clearly referring to Atticus, who think they are helping but they are really just stirring up the black people. It is in response to that comment that Miss Maudie says,

"His food doesn't stick going down, does it?"

She is referring to Atticus's supply of food for the meeting, of course, and she points out directly to Miss Merriweather that she is happy to sit in his home and eat his food while hurling insults behind his back and directly in from of his family (Aunt Alexandra and Scout) and friends (Miss Maudie). This effectively silences Miss Merriweather.