The phrase "turn inside out" implies a reversal or inversion of something, which can be undone by using its antonyms. One such antonym is "right side in," which implies that something is set up properly, with the correct orientation. Another antonym is "keep intact," which means to leave something undisturbed and in its original form. A third antonym is "maintain outside," which implies keeping something on the outside or surface of an object. All these antonyms for "turn inside out" suggest the importance of maintaining the original state of an object or situation.