In the South of the 1930s, a contempt for "Negroes" was universal among all classes of whites; thus, this racial hatred elevated the lower class whites to membership with the higher classes.  This condition is why Bob Ewell insists that his daughter claim that Tom Robinson has raped her.  When he takes the witness stand, Scout describes him as "a little bantam cock of a man."  And, he takes a certain pride in his testimony that derogates the black man because it elevates him to this membership.  He plays upon color rather than worth.

Likewise, Mrs. Dubose feels impelled to call Atticus a n---lover after learning that he will defend Tom Robinson because of this unstated membership. And, Mrs. Merriweather, who is very socially conscious, feels that it is incumbent upon her to discuss the well-meaning, but mistaken intentions of some people in the community and to derogate her maid Sophy when she attends the missionary tea at the Finches' home.  Even Dill's aunt makes the comment that

If a man like Atticus Finch wants to butt his head against a stone wall it's his head

noting that Atticus has broken the social code.  And, Stephanie Crawford adds that it is time that somone

"taught 'em a lesson, they were gettin' way abouve themselves, an' the next thing they think they can do is marry us."

If the jury should break this social code by voting that Tom Robinson  not guilty or in speaking well of Tom, the entire order of Maycomb's society would be  changed.