Can anyone help me find a book just from one quote about a (barrel) organ ?

[Voralfred]

I read this book decades ago, in a paperback edition, rather fat.

But I remember just one scene. Two characters talk about a third one who is a street musician (none of the three a main protagonist). One says casually that the third one was somewhere "playing with his organ" (in fact, a simple barrel organ). The second one asks "With what ?" and the first one repeats "His organ". And what is funny at this point is the reaction of the second one who clearly misunderstood the perfectly innocent intended meaning of the word "organ" in this context. I remember having found the exchange hilarious, especially considering the fact that none of the three was a particularly delicate person. All three were beggars, petty (or maybe not so petty) thieves, maybe even worse criminals, I forgot the details.

[Capn]

Have you read any Terry Pratchett? Just what came to mind, but I apologise - I don't recognize the exact quote myself.