Not so good design

Three engineers are discussing the various branches of their profession, and their contributions.
"It sure looks like the human body was designed by a mechanical engineer", says the one. "Just look how the varous joints operate, how things fit together in supporting and balancing the body."
"Sure", says another, "but what makes the whole thing operate? It's all done by the nervous system, and that's activated by electrical impulses. I would think that it was an electrical engineer that played the major part in the overall design."
"Wrong on both counts", says the third. "It must have been a civil engineer. Who else would have designed for a sewage outlet right in the middle of a recreational area?"