Here’s another example of what I’ll call “the Tweenbot principle” in action:

The onlookers are downright thrilled to witness this unexpected, engaging, and benevolent performance — and rightly so. As I said about the Tweenbots:

… many people are eager for some fresh novelty in their lives. They want to experience interesting things outside the ordinary humdrum of their daily tasks. To a benevolent person, such experiences brighten the mood. They make a day particularly memorable and pleasant. They highlight the simple joys of being a human creature living in a hospitable world.

I need to encapsulate the basic idea here into a single, brief sentence. Any suggestions?

(Via Richard Bramwell.)