"Skeletons in the closet" are things about your past which you would prefer not to tell to other people. Example: "He's a very popular senator but he will never be elected president; he has too many skeletons in the closet." Years after a person has died, only the skeleton remains, and a skeleton of bones can be a frightening thing to look at. "Skeletons in the closet" are embarrassing things which we would like to put away so other people cannot see them. Example: "I don't want anything to do with that guy; he has too many skeletons in the closet." Example: "I had only known her for one week. How could I know what skeletons she had in her closet?"