Leading comedians can't seem to agree on the answer.
But comedy's ultimate taboo which was put to legends including Mel Brooks, Carl Reiner, Sarah Silverman, Gilbert Gottfried, Alan Zweibel, Larry Charles, Jake Ehrenreich, as well as Holocaust survivors themselves in the new documentary The Last Laugh.
It asks uncomfortable questions about just how free speech can really be, with quite hilarious results.
Watch the trailer above.
*Comedian & subject Deb Filler will attend the Festival in Auckland. A Q&A will follow the screenings.
** A FREE Doc Talk: A Joke Too Far, with Deb Filler on Sunday, 4 June at 5.30pm (after the screening) at The Vault, Q Theatre.