The Kitten Torture
The Kitten Torture is a possibly unique method of interrogation and breaking down the interrogée's will to resist, which is employed in the dungeons underneath the Patrician's Palace. It was devised by Moist von Lipwig and approved by Vetinari, possibly to give Cedric something to do that employs the skills-set of an old-time craftsman whose skills are rapidly falling into misuse.
So far, so imagination-feeding.
What actually happens is that a suspect under interrogation is placed inside the Iron Maiden, a device otherwise underemployed under the Vetinari regime. Being a thrifty tyrant wishing to see nothing fall into disrepair if a use may be found for it, Havelock Vetinari was all for this.
Whilst the subject is pondering what happens next, several kittens are placed inside the Iron Maiden with him and the door is closed. In fact, so many kittens go in for company that all the client can do is sit or squat. A large bowl of milk is placed at his feet through a hatch in the modified torture device. Cedric, a man who is kind to and even loves cats, then monitors for signs of feline distress. If the unmistakeable sound of a kitten in distress is heard, he will duly open up and then deliver a roundhouse clout to the client as a sign he is to look after the cats better.
Apparently there were some idiots who thought this was laughable. But it worked so well that after a certain amount of cudgelling to explain to the client what was expected of him, the contented-purr-quotient rapidly rose, and visitors were said to be amazed at the volume of happy purring, which soon filled the whole dungeon. Should Death ever have cause to visit, he would find himself approving of the whole thing, which incidentally made the guest of honour far more prone to disclose everything he knew, from a state of blissed-out happiness.