I wrote a Starsky & Hutch story a few years back called
The Picture In His Pocket, and it dealt with Starksy's father's friendship with mobster Joe Durniak. Part of the story was that Joe had carried pictures of Starksy's father in his pocket for years and he wanted to be buried with those pictures as well. In the story, Starsky says to Hutch "Someday, we'll be a picture in each other's pockets.", which for me was a way to show more about their friendship.
So tonight I caught something on the history channel about Charles Goodnight and Oliver Loving. They were Texas ranchers who were good friends and worked together getting cattle to market along what's now called the Goodnight/Loving trail. When Loving died after an Indian attack, he asked that his body be taken to Texas for burial and Goodnight did. For anyone who's read Lonsome Dove, you'll recognize this, Call does it for Gus after he dies. McMurtry "borrowed" it for his novel.
When I looked the two men up on Wikipedia, I was surprised to find this line: "Goodnight is reported to have kept a photograph of Oliver Loving in his pocket for a long time after his death."
That made me blink. I guess I was right about the type of friendship that makes a person carry a picture in their pocket. Just thought this was kinda cool.