They're nasty, but not in a Filthy Laurie kind of way: "an abnormal passage that leads from an abscess or hollow organ or part to the body surface or from one hollow or part to another and that may be surgically created to permit passage of fluids or secretions." A friend of mine developed one in his nether regions several years ago. Apparently it had been secretly growing since he was formed but waited to burst through to the surface till he was in his twenties. He was not allowed to sit or bathe for many weeks after the surgery. Most unpleasant.
