There’s a fork in the road to Heaven, where one way leads to Hell. At this fork in the road, two twin brothers live who are exactly alike, except that one always tells the truth and the other one always lies.
What single question can you ask one of them to find the way to Heaven?
Point to one of the two ways and ask one brother ‘Would your brother say that this is the way to Hell?’. If he answers ‘Yes’ it’s the way to Heaven, if he says ‘No’, run the other way.