" I found myself wondering if, by whistling about whistling while you work while you were actually working, you would cause some odd bit of the universe, in some unknown dimension, to fold in upon itself—rather like a Klein bottle, which has no inside or outside—causing you to disappear up your own posterior in a cloud of probably invisible orange smoke. "

― Alan Bradley , The Golden Tresses of the Dead (Flavia de Luce, #10)