When Cosca first meets Morveer, he expresses disgust for him, commenting that one of his mistresses was murdered by a poisoner. Morveer objects to being held responsible for the misdeeds of other poisoners, and then thinks to himself about how he was the very poisoner responsible- he had been hired to poison Cosca, and due to a mix-up, Cosca's mistress ended up being poisoned instead.
Morveer's awkward attempts to make conversation with the others/earn their trust are always funny, particularly his "joke" that he had poisoned everyone's bowls, which creates further awkwardness later on when as a nice gesture, he makes soup for everyone.
Morveer's initial attempts to assassinate the banker Mauthis: Under the guise of being a potential client, Morveer goes to see him, and being Crazy-Prepared, continually tries a succession of attempts to poison him, none of which he is able to put into effect because Mauthis does something that makes it impossible (i.e. Morveer wants to stab him with a poisoned ring during a handshake, but Mauthis doesn't extent his hand; Morveer wants to poison Mauthis' wine, but Mauthis declines to drink himself). What makes it funny is that it's hard to tell whether there is actually an I Know You Know I KnowBattle of Wits going on, or if Mauthis is just coincidentally acting in a way that foils each attempt- it's probably the latter, but the fact that Morveer's POV sees it as the former makes it hilarious.
The whole scene where the group hires/interviews various performers/killers to crash a party posing as entertainers. It is like a Terrible Interviewees Montage, except that everyone is hired because they are good (bad) enough for the desired purpose. Also, the whole idea that the protagonists hire a Carnival of Killers says everything you need to know about the morality of the work
Playing into his whole Became Their Own Antithesis plot re the Bloody Nine, there is something funny and ironic about the fact that the random Northman the group hires to mock fight with Shivers at a party (wherein Shivers dresses up as the Bloody Nine), turns out to have sworn a vendetta against Shivers and tries to kill him for real.
The scene that reveals that Shenkt is an Eater is a combination of Bread, Eggs, Milk, Squick that would do Hannibal Lecter proud. Shenkt comes upon a scene of slain mercenaries, and chops off the leg of one woman, musing about the proper cooking of meat and delicious recipes. After collecting the leg, he walks by a bakery and smells the delicious odor of fresh-baked-bread, and thinks to himself how much he would have liked to be a baker (had his life turned out differently) and how good some pate would be on bread. So, he goes back and cuts out the woman's liver.