Recently I've reread parts of Tales of the Norsemen by Roger Lancelyn Green. Who does an excellent job of describing various mythologies (there is a series). Anyway one of the myths described is of Odin and the wise giant Valfthrudnir having a "quiz to the death". As described in the link they agree to ask each other questions until someone gets one wrong and then the winner cuts off the loser's head and keeps it.
I've got a question about this. First up how do they decide weather a particular question is right assuming they disagree? In this tale they don't but what exactly stops a conversation like this happening?
Valf: Which Stallion draws the chariot of the moon?
Odin: It's called "Milky".
Valf: No it's called "Snowy" I get your head!!
Odin: No I'm pretty sure it's "Milky" so I get your head.
How do they go about judging this?