Comic Relief: The porter's speech, which involves drunken rambling and bawdy jokes, provides a moment of levity amidst the dark and intense events of the play. This comic relief helps to break the tension and create a sense of contrast between the serious and humorous elements of the drama.
Allusion to Equivocation: The porter's speech also alludes to the theme of equivocation, which runs throughout the play. Equivocation refers to the use of ambiguous language or double meanings to deceive or mislead. The porter's speech, with its references to "equivocators" and "double tongues," suggests that the play will delve into themes of deception and dishonesty.
By serving these dual purposes, the porter's speech at the beginning of scene 3 adds depth and complexity to the play, blending elements of comedy, foreshadowing, and thematic exploration.