Maybe "turned inside out" isn't getting the right idea across, since the "inside" of an orifice is still a continuation of the outside surface of the organism.

Maybe "turned inside out" isn't getting the right idea across, since the "inside" of an orifice is still a continuation of the outside surface of the organism. Instead picture one of those cabinets with the built-in gloves that are used for sandblasting or handing hazardous materials, and focus on the glove on the right side. Normally a person's right hand would fit inside the glove (which as before is just a continuation of the outside surface of the cabinet). Now pressurize the cabinet so that the glove pops out and inflates. The glove would now be in the shape of a left hand, and if you were to try and put a right-handed glove on it, it wouldn't fit. There isn't really a profound takeaway here, other than maybe they're crediting a a genital arms race for something that is just an accident of related reproductive organs (there's a long list of these types of structures: https://en.wikipedia.org/wiki/List_of_related_male_and_female_reproductive_organs https://en.wikipedia.org/wiki/List_of_related_male_and_femal...).