The Swine King is a decoration and is only received by completing the second Adventure Map.
Once upon a time, Prince Percival was to be crowned the new king of the land. However, he was a haughty character and unpopular with the people. He mocked his citizens and said they should crown a pig instead of him so they would be ruled by one of their own kind.
To the little prince's great astonishment, the people took him at his word and shortly afterwards, King Snout, the first of his name, was crowned the new king of the realm. He reigned over the people for six happy and peaceful years and is still honored today in some circles as the greatest ruler of all time.