Odysseus is trying to get home after the Trojan War. He and his men end up on an island. They enter a cave full of food, but the Cyclops who lives there, Polyphemus, comes in and blocks the entrance to the cave with a huge stone before eating 2 of Odysseus's men
Odysseus gives the Cyclops strong wine, and when he is drunk, Polyphemus asks what his name is. Odysseus tells him that his name is "Οὖτις", meaning'Nobody'
When Polyphemus has fallen asleep, Odysseus takes a poker from the fire, and drives it into the Cyclops's eye. Polyphemus calls for help from the other Cyclops, and they ask who hurt him. He replies with the name Odysseus gave him: Nobody
The next morning, Polyphemus the sheep out of the cave to graze, and being blind, he felt their backs in case the men tried to escape. But Odysseus and his men had strapped themselves to the underside of the sheep, so they escape.
They escape on a ship, and Odysseus calls out his true name. But Polyphemus is the son of Poseidon, so he asks for his father to punish Odysseus.
After his taunting, Odysseus and his men come across further obstacles on the way home, including a storm which Poseidon sends to punish him for blinding his son, Polyphemus.