There's an interesting possibility that our brain actually gives us a neurochemical "hit" every time we encounter a particularly juicy piece of insight porn. The reason for this is evolutionary: insights are basically the recognition of deep patterns that explain seemingly unrelated phenomena, which lets us "compress" our knowledge and so increase our understanding of the world. (It's not that our stone age ancestors were developing scientific theories, but they had many complex things in their environment to predict: the weather, animal behaviour, their own social networks, other hunter-gather tribes, etc).
The pleasure gained from studying mathematics, or listening to complicated pieces of music (esp classical, where complex pieces might be based on simple underlying patterns) are good examples. Humour might be a complementary reward circuit, giving us a psychological hit when we discover something that contradicts our worldview.
(I'm aware that the preceding paragraphs was themselves a piece of insight porn :)