A fleshknuckle is a particularly hard piece of flesh under the skin. This can be caused by rapid weight-loss, or by surgery.
Fleshknuckles are common in people going through mid-life crises.
Hannah and I were having a great time until she discovered my fleshknuckle.
They have boob doctors, cock doctors, and even weird- people-that-want-pointy-ears doctors...why are there no fleshknuckle doctors?