Antonyms for the phrase "most mussed up" could include "neat," "tidy," "organized," "ordered," "well-groomed," "well-kempt," or "clean." These words describe an opposite state of being from the chaotic, disheveled appearance implied by "mussed up." The antonyms suggest someone or something that has been put in order, with everything in its proper place and neatness prevailing. Whether used to describe a person's hair or the state of a room, these antonyms imply an essential sense of organization, control, and attention to detail. By comparison, "most mussed up" invokes images of disorder, neglect, and lack of discipline.