“Oh, all right, Dean, you can come! But, and I want to make myself absolutely clear, you are not to point anything at anything unless I give you a clear instruction, understood?”
“Yes, Mustrum,” said the Dean, meekly.
“Furthermore, you will not, at any point, wave your weapon in the air and shout ‘choc and load’. Is that clear? I say that because I can practically see the silly words forming in your head!”
“That’s a vile calumny!” the Dean shouted.

– on preemptive action |
Terry Pratchett, Ian Stewart, and Jack Cohen, The Science of Discworld III: Darwin’s Watch