Ion was a talented poet who wins first prize in a competition of rhapsodists at the festival of Asclepius, as narrated by Plato. On the road back, he encountered Socrates, and they chatted about Ion and which poets he likes to perform. Ion says he only likes Homer, and then Socrates basically tells him he sucks at life for the rest of the dialogue.

Sickest burn: "No one can fail to see that you speak of Homer without any art or knowledge. If you were able to speak of him by rules of art, you would have been able to speak of all other poets; for poetry is a whole."

(NB: As Socrates didn't leave any of his own writings behind, it's impossible to distinguish the historical Socrates from Socrates as described by Plato et al. These anecdotes are pulled from those writings.)