Happiness Button

Suppose humans were born with magical buttons on their foreheads. When someone else pushes your button, it makes you very happy. But like tickling, it only works when someone else presses it. Imagine it's easy to use. You just reach over, press it once, and the other person becomes wildly happy for a few minutes.

What would happen in such a world?

You could imagine that everyone in the world would be happy just about all the time. People would make agreements with each other to push each othe...