[she] can actually feel her cervix with her finger-if she slides her middle finger back along her vagina as far as possible, she will probably feel something like the tip of her nose with a small dimple in the middle. [http://goaskalice.columbia.edu/curio
Tattoos placed over bones and tendons (spine, neck, back of ankle), on body parts with relatively little padding (feet, hands, joints), and anywhere with loads of nerve endings (nipples, fingers, face) will be the most painful.