Why do Odysseus shout out his real name as he leaves?

Odysseus shouts out his real name as he leaves the Cyclops Polyphemus to assert his identity and achieve a sense of pride and revenge. By revealing his name, he also invites the wrath of Poseidon, Polyphemus's father, which ultimately complicates his journey home. This act underscores themes of hubris and the importance of identity in the epic, as it reflects Odysseus's complex character and his desire for recognition.