The worse thing that can happen to anyone who refuses the full body scan is to be patted down. It has happened to me at least 3 times and, although I don't like it, it is so quick, and so non-intrusive, that its really done before you even know it. A woman always pats down women, and a man always pats down men. They wear gloves, and (at most) lightly insert their fingers around the inside of your belt (or whatever you have around your waist). I guess you are not a frequent flyer?