Ponder looked at the Library doors. A big strip of black and yellow tape had been stuck across them, along with a sign saying: Danger, Do Notte Enter in Any Circumftances. It was now hanging off, and the doors were ajar. This was no surprise. Any true wizard, faced with a sign like ‘Do not open this door. Really. We mean it. We’re not kidding. Opening this door will mean the end of the universe’ would automatically open the door in order to see what all the fuss was about. This made signs rather a waste of time, but at least it meant that when you handed what was left of the wizard to his grieving relatives you could say, as they grasped the jar, 'We told him not to.’
—  Terry Pratchett, The Last Continent