There have been several mentions of this "penis pump" build right into someones mangled shaft.
What kind of sorcery is this?
The actual pump is implanted near the testicles, in the shaft where the "bend" occurs there are inflatable "cylinders" that air is forced into from the reservoir that is implant above the penis. The air expands the cylinders and as the cylinders stretch out and fill, the penis lengthens and becomes hard (due to the air chambers).
You can literally fuck nonstop until your hips/knees/lower back gives out and never go soft once you inflate the cylinders. When you do want to go soft, you find the "trigger" of the pump and press it through your ball sac and let the air out.
Google search will yield photos I am sure.