Periodically, you'll notice some spooky characters roaming around the prison. These ghosts don't really do anything other than float about randomly looking all spooky. When you see one, just follow it around till it either disappears or floats through a wall. If it disappears, find another. They are really common. If it goes all the way through a solid wall, congratulations! You get 10 gamerscore and a few hundred goosebumps for your trouble.