In Chapter 22 of To Kill a Mockingbird, Dill is recounting Aunt Rachel being upset that she didn’t know where he was. He states “Said she was up half the night wonderin’ where I was, said she’da had the sheriff after me but he was at the hearing.” Dill swears that he told her and that she just doesn’t remember. He says, “Bet that woman drinks a pint for breakfast every morning—know she drinks two glasses full. Seen her.”

Aunt Alexandra tells Dill not to say that. “It’s not becoming to a child. It’s—cynical.”

Dill continues. “Tellin’ the truth’s not cynical, is it?”

Aunt Alexandra says, “The way you tell it, it is.”

Aunt Alexandra believes that children should be proper, and that includes having an optimistic attitude toward adults and life. For Dill to not only acknowledge that he is aware of Aunt Rachel’s drinking, but also that she likely “drinks a pint for breakfast every morning,” is a pessimistic, albeit possibly accurate view on Aunt Rachel’s life. He doesn’t believe that Aunt Rachel is even aware of reality because of her drinking, and he says so in a rather crass way that is more fitting of someone older than him.

In the Deep South there are colloquial meanings for some words.  For instance,  the word to aggravate someone is used to mean to irritate or rile that person whereas it does not have that meaning in other geographical areas.  Since the author, Harper Lee, is herself a resident of southern Alabama, there is a strong possibility that the use of the word cynical by Aunt Alexandra in Chapter 22 is given a colloquial meaning since it clearly does not mean its dictionary denotation of distrusting the sincerity of the motives of others as it appears.  There, Aunt Alexandra thinks that Dill tries to deflect his own wrongdoing by criticizing his aunt.  Thus, to her, to make a person look bad in the face of one's own wrongdoing is cynical.  What may be cynical, however, is Dill's suspicion of Aunt Rachel's concern for him. This sentiment is expressed in Dill's remark, "she's just seein' too many snakes in the closet," for with this observation Dill does express some doubt about his aunt's motivations.