Just imagine a little ways into the future, when even more of the tasks currently done by humans are done by robots. Further imagine that the transition is done by companies desperately cutting costs anywhere possible, and therefore not thinking too hard about the possible safety implications of some of these machine-for-human substitutions.

So for example, you go to a plastic surgeon and show him several pairs of pictures. Each pair contains a photo of some feature on your body, and a photo of the same feature on someone else's body the way you want to look.

Unfortunately, the system isn't set up very well, and your photos get a little mixed up.

You feed those photos to a computer, lie down on the operating table, and pass out. A robot scans your entire body looking for things that look like any of the "before" pictures. When looking for your nose, it finds your nose, a small lump in your hair that coincidentally happened to resemble a nose, and your left elbow. It analyzes each one to figure out what part is the right nostril, what is nose hair, etc. It then proceeds to make each of those three places look as much like an ear as possible (that being the picture that got mixed up with your nose picture). However, it doesn't just carve an ear out of your elbow; it believes that it knows what part of your elbow was the bone in your nose and leaves it untouched, while ripping and tearing and rearranging other portions of your elbow so that they would look ear-like had they been the appropriate parts of a nose to begin with. As an end result, you end up with slightly messed up hair, an ear where your nose used to be, and a pulpy, bleeding mass of shredded tissue and splintered bone where your left elbow was.