A play on words with similar sounds or with the several meanings of a single word, to be funny or to say two things at once.
In the Odyssey
No One is my name: No One is what my mother, my father, and all my other companions call me.
"No One" is at once a proper name and a pronoun of negation. When Polyphemus cries out that No One is attacking him, the other Cyclopes will understand that there is no attacker: the play on meanings is visible in the Greek and carries the trick.