Just got back from NYC. The art got shown and sold and all that. At some point soon I may be able to settle back and resume the regular broadcasting schedule here.
Anyway: still testing the hypothesis.
So I just saw Zach Galifinakis interview Bruce Willis and made me think of this player-skill-test mechanism:
NPC (or magic talking box, or communed with deity or whatever) asks a question. If the PC hesitates, horrible things begin to happen.
Unlike the Python "Name/quest/favorite color" gimmick, it's not just a binary answer-or-get-fucked-over situation, it has to get progressively worse the longer the player fails to answer and the player has to know it.
Also, I wouldn't go with a riddle, I'd just go with something that you have to think about for a minute.
Like the cleric goes "Oh, Mighty Vrogthrot, guide me in my hour of need!"
Vrogthrot: "Then tell me, holyman, what is the finest meal you've eaten since you left the Brass Forests of Klee Ten Krhome?"
DM: "You lose a fingernail"
DM: "Tik tik tik. You lose another. Off your thumb."
And then if you lie, things of course get much worse.
Alright, there you go.