I was bored listening to talks at the Las Vegas ACM convention—Association for Computing Machinery; so I left the room and wandered the wide circular hallway of the Convention Center; and a Baldwin concert grand was just sitting there! No one in sight, I sat down and began the 3/4-time first movement of Mozart’s Sonata in F, K. 332.
People always show up when music begins; and in a few moments a lady was standing by the piano. The Convention-Center nurse, in her starched nurse’s cap. Then a sturdy fellow appeared, wearing heavy shoes and khaki work clothes, with tools hanging from his wide belt. He and she both had a bit of gray in their hair.
They listened intently as I played to the end of the movement, and we smiled at each other. He turned to her and bowed and said, “May I have this dance?”
On that same visit, I asked a pit boss at my hotel if someone could really make money playing blackjack using the system in Edward Thorp’s book Beat the Dealer. “If he’s not greedy,” he said politely. “If he’s greedy, we’ll make it impossible.” His face had a slightly amused look; and his eyes kept moving, watching everything, lighting on me for a half-moment at a time. I said, “So you’re aware when someone’s playing the system.” The eyes lit on me for two moments, and he said, “It’s money.” 
