This is a short but revealing conversation that Dill has with Jem and Aunt Alexandra (in Chapter 22). It comes in response to Dill's revelation that his Aunt Rachel is a closet drinker who
"... drinks a pint for breakfast every morning--"
one of the few references to alcohol mentioned in the story. Aunt Rachel is angry because Dill was missing (joining Jem and Scout in the courtroom for the trial), but Dill claims to have
"... told her till I was blue in the face where I was goin'--"
Dill's remark comes as a surprise to Aunt Alexandra who, as a newcomer to Maycomb, is not privy to all of her neighbors' secrets. It is the only mention of this in the story, so we can assume that Rachel keeps her habit to herself. Alexandra calls Dill a "cynic" because she assumes that the story is a lie or an exaggeration; Dill believes his aunt was probably too inebriated to remember that he had already told her where he was going. Of course, Dill is not the most credible character in the story, either, and Alexandra is probably right to question his statement. However, Dill knows what he saw, so if what he says is true, his words are not particularly cynical. In any case, it shows that Dill is slowly growing up and seeing things in a new light; as a "cynic," he has lost his naive view of the things around him.