Lonk

The sharpest, best-trained pilots make worse decisions when they're tired or sick or stressed out, so there's two of them. The most dedicated and experienced air traffic controllers garble an instruction over the radio sometimes, so pilots are trained to always repeat clearances back to catch misunderstandings quickly. The best and brightest maintenance mechanic still overlooks a screw or misconnects a wire once or twice in her career, so aircraft systems are built with two or three or four layers of redundancy, and pilots are exhaustively trained to deal with failures safely. 

Peter Pan edited by Anne Hiebert Alton (2011)

(sorry to interrupt joke post but) this is true!

Children not clapping did happen too, (and some were even expected to have hissed, which was later written into the 1928 playscript and 1911 novel). But my all time favourite anecdote about it is from Pauline Chase (who played Peter)'s intro to Peter Pan's Post Bag 1909:

Children love to clap their hands at the play because then they feel that they are really part of it, and you can see them holding their hands poised ready to seize an opportunity. Their great chance is when I ask them to clap their hands if they believe in fairies, and so save Tink's life. But they are very wrathful if any one claps who has the reputation of being a cynic, and once there was quite an uproar in the front row of the dress circle because of a girl who clapped. Those about her pulled down her arms angrily. "How dare you clap," they cried, "when you know you don't believe in fairies!" There was one dreadfully hard-hearted little boy who came to the theatre not to clap. That was his object for coming, and he came round "behind" to tell me so in the middle of the play. His teeth were firm set. "I won't clap," he said doggedly; "I'm not going to clap." And when the time came he didn't clap; above the clapping of all the others I could hear him shouting from a box, "Peter, I'm not clapping."