Liber gomorrhianus is a book that talks about bad things people can do with their bodies, like hurting themselves or others, or doing things that are not good for their health. The book was written by a man named Peter Damian a long time ago, when people did not talk openly about these kinds of things.
It is called "Liber gomorrhianus" because it talks about a place called Gomorrah, where people did bad things that upset God. The book tries to teach people what not to do, so that they can be good and healthy, and not upset God. It helps people understand that they should take care of their bodies and make sure they do not do things that can hurt them or other people.