In Act 1, Scene 1, Fainall describes the "cabal night" (basically a gossip party) where he imagines Mirabell must have been humiliated the night before. Fainall uses a simile and striking imagery to describe the social dynamic at these parties:
[L]ast night was one of their cabal nights; they have ’em three times a week, and meet by turns at one another’s apartments, where they come together like the coroner’s inquest, to sit upon the murdered reputations of the week.
He compares the party to a "coroner's inquest," an official inquiry where a jury helps a coroner determine cause of death. The dead, in this instance, are not people, but reputations. The comparison to a coroner's inquest is supposed to be derisive. Fainall is scoffing at these people (mostly women) for taking their gossip so seriously. At the same time, there is something serious and sinister about what they are doing. The term "cabal" has antisemitic origins. It refers to a group of organized schemers, often coded as Jewish, who try to exert malicious control over society. Antisemitic groups and conspiracy theorists continue to condemn "cabals" (based on false evidence) for trying to take over the world. Fainall uses the term to convey they idea that the gossip nights are not only ridiculous but also poisonous to society.
The idea that the gossipers are gathering around and sitting on already "murdered reputations" adds to the idea that the gossip parties are distasteful by conjuring the image of a group of scavengers, not just jurists. It is easy to imagine the gossipers as a murder of crows, gathering around to pick pieces off reputations that were dead before they got there. Fainall is proud enough of his simile and imagery, horrifying as it is. By giving him this vivid line, Congreve helps the audience see Fainall as a misanthrope who might have some valid critiques about society but who is at least as bad as everyone else.
In Act 4, Scene 12, Lady Wishfort pleads with Waitwell (who she believes is Sir Rowland) to pardon her long absence to deal with her drunken nephew and his friends. Waitwell's response uses imagery that is laden with verbal irony:
My impatience madam, is the effect of my transport; and till I have the possession of your adorable person, I am tantalized on a rack, and do but hang, madam, on the tenter of expectation.
A rack is a torture device across which a prisoner's body is stretched. While the prisoner's hands and feet are tied at either end, rollers gradually pull the ends apart so that all the joints in the body are pulled apart. The stress on the entire body is very painful. The image of Waitwell hanging on a rack suggests that he is absolutely helpless to do anything because he is so enamored of Wishfort. He is her prisoner. The image is at once flattering and unflattering: he lets Wishfort know that he likes her a lot, but he also chides her a little for leaving him in such a vulnerable position. She is not being a good host, and manners are important to her.
Beneath all this, there is a second meaning to Waitwell's words here. He is waiting "on the tenter of expectation," but not the kind of expectation he allows Wishfort to think. Instead, he is dying to know whether he is going to be able to keep her convinced that he is Sir Rowland long enough for Mirabell to pull off his blackmail scheme. This is a fun caper for Waitwell, possibly in part because he is a servant who now gets to humiliate someone of higher social rank than him. Although his image suggests that he is Lady Wishfort's prisoner, there is a way in which the reverse is true. Because Lady Wishfort is so desperate for attention from a suitor, Waitwell has her captive to his affection. He is gradually stretching her to her limit, seeing how long he can keep her under the spell of his feigned romance.
