A player character had (in another non-harn game world) managed to get himself enslaved for starting a fire in a city (medieval fantasy campaign). He escaped from slavery, only to discover that another player character had done some "dirty and nasty" deed in order to have the slave's owner sign over the papers of ownership to her. In any event, she had to leave the group for a short time, and that was that - the other players continued in the campaign. To make a long story short, the escaped slave managed to do good such that the character got married, had children, and even was granted land for services rendered to a grateful noble. Then the unthinkable happened. The girl returned to the gaming group. After the long absense, she reminded the one player (and the player character via in game interaction), that she still had the slave ownership papers! Thinking that he'd gotten away from the slavery thing because I'd never pressed it all that much (after all, only the slave owner can file a complaint about a run away slave!) as GM, he was literally in shock when she jerked his chain about owning his slave papers. By law, children of slaves are themselves slaves. By law, slaves may not own property - which meant that she could confiscate all of his holdings for her own. The player saw everything he'd worked for begin to crumble about him, and grew unhappy enough that he had his character commit suicide by falling on his sword.
Unfortunately? Committing suicide is a major sin in the campaign world, subjecting the sinner to the depths of hell. Well, the girl felt so bad about the suicide, that she arranged to try and open a gate to hell and rescue the poor soul so that the resurrection spell could work. Being tired that night as a GM, I devised what I THOUGHT was a simple yet elegant solution. Rather than run a game run where the player characters were in Hell (via the gate mind you!), I just had the party met by a rather tired and overworked demon saying "Look, here's the deal. I shall submit to you, but one question. If ANY one of you gets it right, then you all can take your friend's soul out of here. If none of you get it right, then you all admit your souls belong here. Deal?"
As GM, I reasoned thus: Give them a question that can only be answered with a YES or NO. With three people answering the question - a smart individual would realize that if one answered YES, and one answered NO, between them, they would have ONE correct answer. A win win situation for everyone.
"Do you wish your friend were where he belongs?"
It was a trick question, because the soul of the damned was already where it belonged! First player without thinking yelled excitedly... "YES!", sure that he had the right answer. Then a look of horror crept over his face and he groaned almost inaudibly... "No!". Looking to the girl in the group (by girl, she was about 20 at the time), She too very confidently said "YES!". Upon hearing the other guy groan after saying yes, she too realized the error of her ways and also groaned. The third and final player - the one who was using a "loaner" character on the off chance the party could get his "suicided" character out of hell, confidently said "Yes" - this despite the fact that the other two had answered "yes" and then groaned afterwards. Time between when the first person answered to when the second person answered? At most, two seconds. Time between when second person answered and third person answered? About 30 seconds.
Afterwards? After a major battle to reach the gate and escape hell, the two players looked at me and called me a bastard for setting it up that way. When I explained to them that all they had to do was have one player say "Yes" and one player say "No" and all of this would have been avoided, they just looked even more unhappy. Whether with me or themselves, I can't say. I must admit, they almost DIDN'T get their characters to the Gate before it closed, and had they taken more magic items and stuff with them, I would have been able to make their characters pay far more dear a price than they did. But then again? They could have avoided it all simply by thinking "Hmmm, only one of us has to get the answer correct, and the question can only be answered with a yes or no - simple, one answers yes, one answers no."