altruistic bet on just-dice. Let me bet 10btc on roll hi and we split profit and i return the original bitcoin if i win. If we lose, then we lose together.
send me the bitcoin to 1fbii5eU7zXCe1yn4pchhojCTgVT1xnwE
So if you "lose" you're out nothing while the other guy is out 10 btc.
You didn't think more than 5 seconds about this idea, did you?