During its heyday, the Wells Fargo Company employed a number of specialized stagecoaches such as one with a church for Sunday operation. One of the more popular models featured a darkroom on board, so passengers who took pictures could have them processed en route and the prints delivered at their destination. 

One day a stagecoach equipped with a darkroom was headed for Wichita when, passing through a small town, it was intercepted by the local marshall, who said, "Halt in the name of the law!" 

"What's the problem?" the stagecoach driver asked. 

"You should know that the operation of a mobile darkroom is illegal in Kansas," the marshall said.

At this point two psychologists on horseback arrived on the scene. One of them said, "I suppose what we have here is a classic case of the Oedipus complex." 

The other said, "No, it's much simpler than that -- it's just an arrested stage of development."