Imagine you are going about your day when suddenly your head feels strange. Information comes to you, you know things that you didn't a moment before, things about what is about to happen. Soon humanity will be different. People will from now on go through a second puberty in their early twenties during which men will grow breasts and gain a whole female reproductive system in addition to their existing male one. Women will grow a functional penis while keeping their vagina. People's sexuality will change during their second puberty to make them attracted to the new version of their preferred gender. In a short while your body will change to be the one you would have had if the second puberty had always existed. Your clothes will not adjust, your past won't change, just your body. It will only take a minute or so.