The Shockwave spread across the earth, starting at the north pole and terminating at the south. For whatever reason, compleatly altering human anatomy as it past over our world.
The momment that the Shockwave hit them, any fertile woman would have their vagina close shut and fade away, and in their place a large masculine penis would form. Suddenly, every woman on earth would find herself with masculine anatomy, potentially forever.
Men are seemingly unaffected by the transformation, meaning that basically everyone is now dealing with the same equipment. How humans will reproduce is still a mystery, as is how society will change now that women have the same parts as men.
We cut to a young woman whose just been transformed...