In Ancient Persia, a criminal would be placed in a tree trunk with only head, hands, and feet sticking out. Then they were force fed milk and honey until they get crazy diarrhea. Near, or on, a pond, their exposed skin was covered in honey to attract the attention of insects and as their shit began to pile up, more and more insects would gather. The insets would eventually use the person's skin as a breeding ground as it turned gangrenous. Death would be a welcome occurrence but could take up to two whole weeks!
Could anything possibly be worse than that?!