Comic Relief and its Function

In Act II, comic relief lightens the scene after Angelo condemns Claudio to be executed. In enters a character named elbow, whose dialogue in itself is humorous and somewhat ironic. Elbow states, "If it please your honor, I am the poor duke's constable, and my name is Elbow: I do lean upon justice, sir, and do bring in here before your good honor two notorious benefactors." First off, it is just funny how he makes an allusion to his name by saying he "leans" upon justice. Next, he makes an oxymoron by stating "notorious benefactor," which really don't make sense when used in conjunction with one another. Other parts of the conversation are similarly entertaining, despite what they are talking about.