The Nipple Pain Test

Lets see how noisy my slave can get when I test my high-heeled slippers on him. I have chosen some of my footwear for this experiment in slave volume. Which shoe feet and high-heeled shoes inflict the most extreme torment on his nipples and cause him the mosst pain? With which of my mean shoes will make the slave scream the most loudly? I will find out now by totally fucking-up jis nipples!