Odysseus reveals his true identity to Polyphemus because he is absorbed in the moment. He has just designed an ingenious escape and blinded a cyclops, and, caught up in the glory of the moment doesn't think about the consequenses of his actions. Hubris (excessive pride) is one of his character flaws.
When Odysseus and his men landed on the island of the Cyclopes, they encountered a giant named Polyphemus. Curious about the Cyclops, Odysseus and his men entered his cave, only to be trapped when Polyphemus returned and began to eat them. To escape, Odysseus devised a clever plan, getting Polyphemus drunk and telling him his name was "Nobody." After blinding the Cyclops, Odysseus and his men fled by clinging to the undersides of Polyphemus's sheep, but Odysseus's pride led him to reveal his true identity, prompting Polyphemus to curse him.
Polyphemus, the Cyclops, captured Odysseus and his men when they ventured into his cave. He trapped them inside and began to eat Odysseus's crew one by one. To escape, Odysseus cleverly devised a plan, getting Polyphemus drunk and blinding him with a sharpened stake. After escaping, Odysseus taunted Polyphemus, revealing his true identity, which led to further consequences from the Cyclops's father, Poseidon.
The Cyclops, Polyphemus, realizes the true identity of Odysseus after he calls for help from the other Cyclopes. When they come to his aid, Polyphemus tells them that "Noman" is blinding him, leading them to think he is simply afflicted by a divine punishment. However, when Odysseus reveals his true name, Polyphemus understands that it was Odysseus, the clever man who outwitted him, thus uncovering his identity despite the initial ruse.
Odysseus and his men escape Polyphemus' cave by cleverly deceiving the Cyclops. After blinding him with a sharpened wooden stake while he is drunk, they hide underneath the sheep as Polyphemus lets them out to graze. As they make their escape, Odysseus reveals his true identity to the blinded giant, provoking Polyphemus to curse him, which leads to further troubles for Odysseus on his journey home.
After Odysseus reveals his true identity to Polyphemus, the Cyclops prays to Poseidon to take revenge on Odysseus. He asks Poseidon to make Odysseus's journey home difficult and filled with suffering, ensuring that he never returns to his homeland or that, if he does, he will find his home in chaos and his family in ruin. This plea for vengeance sets in motion a series of challenges for Odysseus during his voyage.
He did not say anything to Poseidon; rather, he blinded Polyphemus, the god's cyclops son, because of his pride (his hubris) Odysseus revealed his true identity to the cyclops, and in return Polyphemus told his father (the resulting hamartia.)
He revealed his true identity because he was boasting about being clever and stuff. He wasn't being very bright, as usual.
He tells her about their bed and how its made out of the olive tree and immovable. Only something that Odysseus and her knew.
As Odysseus is leaving the Cyclops Polyphemus, he makes the critical mistake of revealing his true identity. Instead of escaping quietly, he taunts Polyphemus, proclaiming his name and boasting about his cunning. This act of hubris provokes Polyphemus to curse Odysseus, leading to further challenges and obstacles during his journey home. This moment highlights the dangers of pride and the consequences of revealing one's identity to enemies.
Odysseus escapes Polyphemus's cave by employing cunning and trickery. He tells the Cyclops that his name is "Nobody," so when he blinds Polyphemus with a sharpened stake, the giant's cries for help go unheard, as he claims that "Nobody" is attacking him. To flee the cave, Odysseus and his men hide under the sheep as Polyphemus lets them out to graze, allowing them to escape unnoticed. Once they are safely at sea, Odysseus reveals his true identity, provoking Polyphemus's wrath.
Odysseus and his men then took the timber and heated the sharpened end in the fire until it glowed red. Then, with all their strength, they pushed the red-hot point into the eye of Polyphemus. The Cyclops howled and woke up flailing, but he was now blind.
Odysseus' decision to stay at Polyphemus' cave proves disastrous. When the Cyclops returns, he kills several of Odysseus' men and eats them. Odysseus manages to escape, but his blinding of Polyphemus, who was a son of Poseidon, has terrible consequences. When Odysseus finally reveals his true identity to Polyphemus, the monster prays to his father for vengeance. This prayer brings about Poseidon's persecution of Odysseus and in Odysseus' return from Troy being significantly delayed.