This expression was suggested by a former co-worker and friend who reminded me of a mutual project where somehow the drawings of a waste disposal drum indicated, obviously absurdly, that the inside diameter was larger than the outside diameter. “Blivet” was the term used by the U.S. Army in World War II for “ten pounds of manure in a five pound bag.” Mad magazine had a corresponding term “three-pronged poiuyt” on the March 1965 cover. The term is used to describe something really ugly, unmanageable, damaged, or even a self-important person. You really need to look at the Wikipedia link to understand the impossibility of the illustration.