A violist couldn’t find a babysitter for rehearsal, and had to bring his 4 year old along. The conductor was dubious, but the violist swore his kid would be super quiet, just look at some books, and listen to the music. Reluctantly, the conductor agreed.
Halfway through the rehearsal, the conductor was impressed. True to his word, the violist’s kid hadn’t made a sound. But suddenly, the violist smacked his child! Even so, the child merely whimpered a little and stayed quiet. The conductor was shocked, but kept going.
Afterward, the conductor rounded on the violist. “Hey, your kid was being perfectly quiet–why on earth did you hit him?!”
“Well,” replied the violist, “he detuned one of my strings.”
“OK, that’s not good,” said the conductor, “but I don’t see why you’d react so terribly to it.”
The violist looked angry. “He wouldn’t tell me which one.”