Show that humour in the drunken-porter soliloquy springs from the following sources: topical allusions, dramatic irony, pun, euphemism, irony.Act 2 scene 3
I love this scene. I will address each of your sources individually.
Topical Allusions - The porter refers to "Beelzebub," an agent of the devil, "the everlasting bonfire" and to the door being "Hell's Gate" in this scene. All these allude to hell and a spirit of evil in the castle. This is appropriate because the castle now represents a hellish murder scene with evil lurking everywhere.
Dramatic Irony - Dramatic irony is defined as the audience knowing something that the characters do not. The porter scene allows the murderers, Macbeth and Lady Macbeth, to wash up and get to bed before Macduff enters to catch them in the act. Ther readers know this. The slow-moving stumbling porter takes a long time to answer the door, and even then, he engages Macduff in silly conversation before fully admitting him.
Pun - Shakespeare makes a pun on the word 'lie' in this scene. He refers to lie as being in bed when Macduff asks him,
Was it so late, friend, ere you went to bed, That you do lie so late?
Later the same word is used to also mean to fib or tell an untruth when the Macduff comments:
I believe drink gave thee the lie last night.
and the porter replies,
That it did, sir, i' the very throat on me; but I requited him for his lie;
Euphemism - A euphemism is used to make a lewd or uncomplimentary situation sound a bit nicer. In this scene, the porter tells Macduff that dangers of too much drinking on sexual performance. However, he never uses the word 'sex' or any names of body parts. Instead, he uses the following euphemistic language to refer to the effect of drinking on sexual desire and performance:
it makes him, and it mars him; it sets him on, and it takes him off; it persuades him, and disheartens him; makes him stand to, and not stand to; in conclusion, equivocates him in a sleep, and, giving him the lie, leaves him.
Irony - In addition to the dramatic irony discussed above, some verbal irony exists in the responses the porter gives to Macduff. He is not respectful to Macduff as he should be, instead blaming him for waking Macbeth with his knocking.