you're in a room with two doors. if you walk through one, you'll die. if you walk through the other, you'll live. there's a man in front of each. one of them always lies. one of them always tells the truth.

you can ask one question.

what question can you ask to figure out which is the safe door to walk through?

i.e. what color is your shirt would work to figure out which one is honest if you could ask two questions. but since you can only ask one, you need a question that is more encompassing/revealing.

and, don't bother asking me for the answer. i don't know the answer. this morsel dances into my head for a few minutes every few months to tantalize the workers in my brain. while it's there they all lean on their shovels and push back from their desks and look at the show until they get headaches. then they resume the ditch-digging and paperwork causing it to leave the room. now i pass it on so your brain's workers can be occasionally distracted (and annoyed) too. no need to thank me. i can see it in your eyes.