What secret does Dolphus Raymond reveal to Scout and Dill out side the courthouse? how does it change the way they think of him? What is his explanation for why he "deliberately perpetuates a fraud aginst himself"?

Mr. Raymond reveals that his brown paper bag does not hold alcohol..... only a bottle of cola. He allows people to think he's a drunk, so they don't bother him or question his actions. Dolphus is married to a black woman, and he thinks that by letting people think he's an alcoholic, he gives them a reason for what they see as odd behavior.