Imagine that a group of SF fans in Berkeley, mid-60's, under the heavy influence of J.R.R. Tolkien and who knows what else, decide to have a "tournament" theme party. Then imagine that it gets to be so much fun that they do it again, and again, and again...and before long, people start taking it seriously. They start to care who the king and queen are, take oaths of knighthood, and develop into a "society."

Then imagine that they decide to call themselves a historical education group so that they can get non-profit status and look respectable. But some people think that they're serious, and so they start trying to make their costumes look something like what medieval people would actually wear. And they start trying to get other people involved.

Now imagine that the group starts to spread and in 30 years it has 100,000 people who spend time in a parallel universe that's made up of equal parts serious research into the history of the Middle Ages, Victorian fantasy, and Heinlein-inspired libertarianism. You could even pretend that one of the early kings, a person who still remains influential, is Milton Friedman's son and was crowned around the time that he was helping to organize the Libertarian party.

Now consider that this thing actually functions, and they call it the Society for Creative Anachronism (SCA). There are chapters almost everywhere in North America and in many parts of Australia and Europe.