Pierce their big toe(s)
More about Pierce their big toe(s)
How high is your pain threshold? This is hardcore: Pierce your big toe with a sterilized hypodermic needle so that the needle passes through the toe as shown in pictures (My toe pierced with 16g needle). You can choose your needle gauge size. Use larger gauge needles and pierce the toes on each foot, if you can withstand the pain. Better still, pierce the toe(s) with a piercing needle and insert a barbell. (Piercing needles are more painful). If the big toes are too challenging, then pierce the smaller toes instead.
WARNING: make sure you pierce through the soft flesh. Don't go anywhere near the toe bone (phalanges).