The first riddle I ever heard, one familiar to almost every Jewish child, was propounded to me by my father: "What is it that hangs on the wall, is green, wet -- and whistles?" I knit my brow and thought and thought, and in final perplexity gave up. "A herring," said my father. "A herring," I echoed. "A herring doesn't hang on the wall!" "So hang it there." "But a herring isn't green!" I protested. "Paint it." "But a herring isn't wet." "If it's just painted it's still wet." "But -- " I sputtered, summoning all my outrage, "-- a herring doesn't whistle!!" "Right, " smiled my father. "I just put that in to make it hard."Leo Rosten, "The Joys of Yiddish"