In this paper body scanners, which bounce X-rays off people, penetrating their clothing to reveal concealed objects are discussed. The scanners have become common in the US, and in the UK the bulky step-in booths are already installed at Gatwick, Manchester and Heathrow airports as a kind of enhanced security option to the decades-old metal scanners. The point about the new scanners is that they are supposed to catch terrorists who smuggle non-metallic items In their clothing, such as powders or ceramic knives; in short, another 'underpants bomber'.