I think the phonebook sword routine fooled them only because they overthought it. He absolutely held the break and peeked, and that's all there is to the trick. The rest was Penn not really paying attention, and Teller not catching his big mistake: calling impossible numbers.   Jonathan picked a page at random from the fan while the magician was not looking. The back of the phonebook was to the audience, which obscured what he was doing with his other hand. Jonathan wrote down the page number,