In Chapter 6 of To Kill a Mockingbird, the racist and prejudiced nature of the community is revealed as Nathan Radley blames a black man for trespassing on his property one summer night. He shoots a bullet into the air and all the neighbors come out to see what happened. Little does the neighborhood know that it was one of their own who actually did the trespassing: Jem Finch.
The text doesn't reveal if Nathan Radley really saw that it was a child he was shooting at that night. If he had truly known that he was shooting at a child, he probably wouldn't want to admit that to the neighborhood because he might seem unjustified. But if he tells his neighbors that he was shooting at a black man trespassing in his yard, then he is bound to gain favors and understanding rather than social disapproval. It seems to be easier for people to blame scary or difficult situations on black people, disabled people, or just about anyone who is different or in a socially lower class. It is lucky for Jem that Nathan Radley does blame a black man; otherwise, he may have gotten into some major trouble with the Radley's as well as with his father.
It is Boo Radley who is usually blamed for any "small crimes committed in Maycomb," but since Mr. Radley must have known that Boo was inside the house (or at least on the porch), he blamed the trespassing on the next logical choice: A Negro. It was not likely that any black man would be lurking at night on a white man's property (since a shotgun blast was the probable result), but Mr. Radley's guess as to the color of the culprit's skin would probably have been echoed by most of the other townspeople. Miss Stephanie's crude attempt at humor was an attempt to make light of the situation:
"Shot in the air. Scared him pale, though. Says if anybody sees a white nigger around, that's the one."