I see the discussion has completely derailed. :-)
It seems what I posted sounded like a betting system, which it isn't.
Here's an EXAMPLE - I should but that in bold and red - of what it COULD look like. All the details are subject to change, I'm just trying to illustrate the concept, so don't start digging away at the details.
John is a duke of some realm who would really like to see some more action. He does have his eye on a region bordering his duchy, but belonging to another realm. So he puts in a challenge, in this case to himself, that the region will become part of this realm within 3 months. He does it for honour, so if for whatever reason the region does become part of his duchy, he will gain some honour. If it doesn't, by the time limit, he will lose some. Since challenges have to be accompanied by a message, he makes a public posting basically saying whatever but it should at least hint at his goal.
Jack is had enough of John's ambitions, but as a lowly knight he can't really confront him directly. So he challenges him. In a message to Duke John, he details his (made up) claims towards the currently vacant lordship of one of the regions, demanding to be appointed as its lord. His secret challenge is easy to guess - become lord of that region. But John can, in accepting the challenge, put up his own stakes. His response message denies the claims and calls Jack a forger. The secret stakes - again easy to guess - are honour. If Jack somehow becomes lord of the region within some TBD time frame, his claims were obviously true and John will lose honour for doubting them. If he doesn't, then Jack will lose honour for apparently being indeed a forger, or at least employing one.
That's really a very rough sketch, alpha quality at best. Needs lots of work.