What is the symbolism of the Halloween costumes that Justyce and the others wear to the party?

The Halloween costumes are exegetic symbols, satirically using stereotypes to prove that racial inequality is over. Exegetic symbols are symbolic to the characters within the novel, not just to the reader. Jared’s idea is that the stereotypes that were once barriers to equality and friendship are now over, so they are no longer hurtful and can be fun costumes.