Answer:
After Odysseus and his men encounter Polyphemus, the heroe demands the traditional custom of hospitality.
However, the cyclops refuses, arguing that he did not fear the rage of the gods, and proceeded to eat two of Odysseus' companions.
After seeing the cyclops' folly, Odysseus came up with the plan to get Polyphemus drunk with pure wine and then stab him in the eye.
After giving the cyclops the wine, which Polyphemus liked greatly, he says that his "gift" to Odysseus will be to eat him last.
This goes against the Xenia, the Greek custom of hospitality by which men took in foreigners, feed them and offered them gifts, for the god Zeus was the protector of all wanderers.
