Take a black, wide-nibbed marker. Destroy all references to character levels and XP. Copy out the below into the margins of your rulebook.
A Character who makes a Boast of Heroic Proportions either gains 1HD or +1 Attack Bonus in addition to any wager or reward offered by others.
If they are found to shirk their Boast, they lose the HD or Attack Bonus and may never again Boast.
Those failing the Boast lose the HD or Attack Bonus, but may try again or make another Boast.
Only one Boast can be pending at a time.