The king has proposed a contest of intellect.
You have a balance scale and twelve identical looking spheres of gold - except that one is either heavier or lighter than all the rest. Using the scale and only 3 measurements, you must determine which is the 'odd ball' and whether it is lighter or heavier.
If you fail, you get to be court jester for a month. The king has a terrible sense of humor - trust me; you don't want to be court jester (even for just a month). It's part of the reason he holds this contest. It's the only way he can get anyone to 'sign-up' for the job.
If you can correctly guess the 'odd ball,' but not whether it's lighter or heavier than all the others, you get to go free.
But if you can get the right ball AND figure out whether it's lighter or heavier - you get to keep all twelve spheres of gold. They're worth a small fortune - enough to buy your own keep - which would raise you up from lowly Surf to rich Landowner in the blink of an eye.
What do you have to lose - except your dignity...