He must be using an iOS file manager such as iFile. I used to do this on Classic. Let us say you want a cool new head. You can replace the head you don't want with a head you do want. Say I don't like head3.png. I can rename the head I want to head3.png and delete the real head3.png. This isn't hacking at all. It only shows up on the screen of the person who edited the files.