One of many examples of pawky humour in The Hobbit.  A few pages later the same trolls are discussing what to do with the dwarves they have captured: ‘arguing whether they should roast them slowly, or mince them fine and boil them, or just sit on them one by one and squash them into jelly.’

‘Yes, I’m afraid trolls do behave like that, even those with only one head each.’

Source: JRR Tolkien, The Hobbit (London: HarperCollins, 1995), p. 33 and 38