Slug

I have a friend called Slug.  It's not his real name, of course, that's just what we all came to call him.  Slug suffers from a very rare, very terrible, degenerative disease that has caused all his bones to slowly disintegrate beginning at the onset of puberty.  Fortunately, the destruction of his skeleton was so gradual that certain operations could be performed, allowing him some semblance of an inner structure.  While it was deemed necessary for his skull to first be reinforced and finally completely replaced with a tough plastic shell, his body is now kept upright by a system of air-filled bladders, each painstakingly inserted under his skin, with their little valves for topping up at his joints.  Sometimes as a prank, somebody would switch his air tank for one full of helium.  The first time, poor Slug hit the roof.  After that, he always made sure to keep some weighty reading material around, just to keep his feet on the ground and his head out of the clouds.  He was once heard to remark that it was actually easier to drift off to sleep while under the buoyant influence of helium, but that was no excuse for people to go around sneaking these things on him.  Those air bladders lasted some years with no problem but the foreseeable air loss, which was fixable through the valves, but after a decade or so, their material began to degrade.  Slug began to suffer embarrassing blowouts and breakages.  Sometimes he would be seen dragging himself around town with one limb limp and flat.  One dreadful night, he suffered a major air pressure loss while showering and the last anybody saw of him was what his roommate said was probably his left hand, spinning slowly as it followed the rest of his breathless body down the drain.  If he happens to surface from your plumbing, his friends would be most grateful for his return, to the extent of reimbursing postage.  Just be sure to make a couple of air holes in the box.