The goblins have Gandalf, Bilbo, and the Dwarves treed and are burning the trees as they being to sing:

Fifteen birds in five firtrees,
their feathers were fanned in a fiery breeze!
But, funny little birds, they had no wings!
O what shall we do with the funny little things?
Roast ’em alive, or stew them in a pot;
fry them, boil them and eat them hot?

Submitted by Nauma