"These must be the very three that were caught by Gandalf, quarrelling over the right way to cook thirteen dwarves and one hobbit."
Troll pondering its age, Theodor Kittelsen
Public DomainTroll pondering its age, Theodor Kittelsen - Credit: wikimedia commons
This is a reference to an episode in The Hobbit, when three trolls captured Bilbo and the dwarves. They were so absorbed with arguing over how to cook their dinner, that they were caught by the dawn and turned to stone.

Trolls can be found in Norse mythology as strange and sometimes magical creatures, humanoid in appearance, and ranging in size from giants to smaller folk living in caves. They are not always evil, but often devious, dangerous or tricky. Trolls are also common in fairytales and fantasy fiction. In the latter they are usually portrayed as large, brutish and stupid monsters that have a taste for human (or dwarf/hobbit) flesh, as in The Hobbit.