What is an example of how Shakespeare uses dramatic irony in Act III of Romeo and Juliet?

Dramatic irony, of course, is created when the audience (or readers) know something that the characters onstage do not. One example of dramatic irony in Act III of Romeo and Juliet occurs when Tybalt and Romeo fight in the streets of Verona. The fight occurs when Mercutio challenges Tybalt, whose challenge to a duel has been declined by Romeo. Mercutio views this as "vile submission," and enters the fight on behalf of his friend. What neither of them realizes, as Romeo tells them, is that he has a good reason not to accept Tybalt's challenge: He has by then become Tybalt's kinsman through his marriage to Juliet. When Romeo says that Tybalt (and Mercutio) does not "know the reason of my love" for him, the audience does know. This is an example of dramatic irony, as the audience knows the death of Tybalt (which violates the Prince's edict against fighting from the beginning of the play) will have disastrous consequences for the newly-married Romeo and Juliet.