I had been telling Holmes about a visit I had once had from an American acquaintance, when he sprung a rather odd question on me:
“Watson,” he asked, “do you suppose that it is legal in New York for a man to marry his widow’s sister?”
“Legal? Well, yes,” I replied, “but frowned upon, I should think.”
At this Holmes chuckled. “Frowned upon, indeed! Oh, Watson, you do amuse me.”
Why did Holmes find my answer so funny?