It comes up a lot, long after it’s been thoroughly debunked, but just in case you missed the memo: No, your nails and hair don’t continue to grow after death. Dying is undeniably grim but it, fortunately, doesn’t involve this bizarre, continued extrusion. So why does everyone think they do?
When you shuffle off your mortal coil and join the choir invisible, as some marvelous chaps once said in a pet shop, your body begins to dry out. This dehydration causes your skin, as well as other soft tissues, to retract, but your hair and nails remain intact. This, then, can sometimes give the appearance of growing hair and nails post-mortem, but it’s an illusion, nothing more. No more beautiful plumage for you, ex-human.