An infernal machine.
(Click on the image for larger size.
Progress in Research: Chapter Four, Page Twenty-Four written and commissioned by Dr. Faustus of EroticMadScience.com and drawn by Lon Ryden is published under a Creative Commons Attribution-NonCommercial-NoDerivs 3.0 Unported License.)
You see, this is why nuns should not be allowed to watch hentai. It gives them ideas.
Image source lost by me, unfortunately.