This busy scene begins with a moment of light comedy, which serves to heighten the suspense. The porter of Macbeth's castle, drunk from the previous night's revels, complains that his job is worse than that of the porter of hell. In a private game with the audience, he engages in a piece of stand-up comedy in which he imagines himself as that beleaguered servant, opening and closing the gate on the damned. The first two examples he uses (that of a farmer and an equivocator) have specific religious and historical connotations. A few months before Macbeth was performed at court in front of the Protestant King James I, the infamous Gunpowder Plot (the aim of which was to murder the English king) took place. The conspirators, including Guy Fawkes, may have been encouraged by a Catholic convert called John Garnett, whose nickname was "farmer." The practice of lying in court about one's religion by employing confusing or ambiguous language was known as equivocation. Many examples of ambiguous language are heard throughout Macbeth, and of course the words of the Witches themselves are not entirely clear. So the porter's examples are not entirely without significance, even though they may be unintentional.
The humor continues when the porter unbolts the door to Macduff and Lennox and offers a series of bawdy jokes, momentarily distracting the audience from the fact that Macbeth must at this very moment be washing his hands of the blood of the previous scene. Then Macbeth enters, apparently at ease, to direct Macduff to the king's room.
