In the Clouds, Aristophanes has a good go at Socrates and Chaerephon. A student is saying what a brilliant teacher Socrates is to an old man who wants to enrol in his school so he can learn to argue, and get out of paying the debts that his son has run up.

Student: Chaerephon once asked him whether gnats' buzzing comes from their mouths or their arses.

Old man: And what did he say?

Student: He said that a gnat's gut is a narrow tube. Because of this, wind is forced out through the arse, making it resound as it does so.

Old man: So a gnat's arse is a trumpet? How utterly brilliant! An expert on gnats' guts will help get me off my debts with ease!