"I will give you an example," the major had said. "Do you know what is meant by "Horrors of War' cards?" He had eyed Chidan with avidity.
Searching his memory, Childan had at last recalled. The cards had been dispensed, during his childhood, with bubble gum. A cent apiece. There had been a series of them, each card depicting a different horror.
"A dear friend of mine," the major had gone on, "collects 'Horrors of War.' He lacks but one, now. The Sinking of the Panay. He has offered a substantial sum of money for that particular card."
"Flip cards," Childan said suddenly.
"We flipped them. There was a head and a tail on each card." He had been about eight years old...
Considering, Major Humo had said, "I have heard my friend discuss his 'Horrors of War' cards, and he has never mentioned this. It is my opinion that he does not know how these cards actually were put to use."
Eventually, the major's friend had shown up at the store to hear Childan's firsthand account.
Philip K. Dick, The Man in the High Castle