The year is 2016 and we officially live in the age of the penis transplant -- and while the notion may stir giggles from some, there's nothing humorous about the cancer survivors and wounded soldiers who can benefit from such surgeries. In this episode of Stuff to Blow Your Mind, Robert and Christian discuss recent advances in penile transplant surgery and chat with author Mary Roach, who devotes two chapters of her new book "Grunt: The Curious Science of Humans at War" to urotrauma and genital transplant surgery.