After Ralph throws his spear at a wild boar that runs through the bushes, Jack chases after the creature, wounding his arm in the process. The boys become overexcited by all this action and decide to re-enact the scene with Robert volunteering to play the boar. Thing rapidly get out of control, as the boys "pretend" to stab Robert with their spears and scream, "Kill the pig! Cut his throat! Kill the pig! Bash him in!" Robert is left terrorized and sniveling by this "game," despite being physically intact.
This mock hunt is significant because it helps expand the group mentality that is developing within the boys and the thirst for violence that is lurking behind their carefully constructed exteriors. Robert suggests that the boys "want a real pig... because you've got to kill him," and this certainly appears to be true; the boys know that it was not nearly as satisfying to pretend to kill as it would be to actually kill. The boys are losing their humanity and their sense of being in contact with the civilized world and moving towards a more savage ethos. This, of course, is not the last hunt; they have gained a dangerous confidence that will enable them to kill (both a pig and a boy) later in the book.