Scaphism

Scaphism, also known as the boats, is an ancient Persian method of execution designed to inflict torturous death.
The naked victim would be firmly fastened within a back-to-back pair of narrow rowboats (or in some variations a hollowed out tree trunk), the head, hands, and feet protruding from this improvised container.
The victim was forced to ingest milk and honey to the point of developing severe diarrhea, and more honey would be rubbed on his body so as to attract insects to the exposed appendages. They would then be left to float on a stagnant pond (or alternately, simply exposed to the sun somewhere). The defenseless victim's feces accumulated within the container, attracting more insects, which would eat and breed within his or her exposed (and increasingly gangrenous) flesh. Death, when it eventually occurred, was probably due to a combination of dehydration, starvation and septic shock.
Death by scaphism is painful, humiliating, and protracted.