What's green, hangs on a wall and whistles? [A Herring]
"The Joys of Yiddish". Book by Leo Rosten, 1968.
![What's green, hangs on a wall and whistles? [A Herring]](http://cdn.quoteddaily.com/images/leo-rosten/whats-green-hangs-on-a-wall-and-whistles-a-herring.jpg)
What's green, hangs on a wall and whistles? [A Herring]