Immediately preceding the first production of Shakespeare's Julius Caesar in 1599 was a romantic comedy called The Shoemaker's Holiday by Thomas Dekker (c.1572-1632). Some scholars believe he had a hand in editing some of Shakespeare's plays. Patrons to the theatre during the Elizabethan Age might see productions back to back; frequently the actors would perform one play in the morning and another at night. Those watching the opening to JC would clearly recognize that Shakespeare was spoofing the preceding play, ever so briefly through the character of the cobbler, before getting down to the serious business of conspiring against and murdering Caesar.
Shakespeare often uses simple people for comic relief in his plays. Fools, jesters, merchants, etc. In Act I of Julius Caesar, several "commoners" are milling about in the streets, not working, celebrating Caesar's latest victory. An exchange of words takes place between these commoners and Flavus and Marullus, who call them "idle creatures" and chide them for not working. They parry back and forth and, believe it or not, the exchange would have been quite humorous in Shakespeare's time. For example, the cobbler puns: "I am a mender of bad soles" - foreshadowing, in a humorous way, that there are going to be some "bad souls" in the play that will need mending. Read carefully the words of the "second commoner" and look for hidden meaning in his words. Shakespeare uses humor to foreshadow the tragic events that are to follow in the play.