Imagine you are lost in a far away land. Now you see two paths. One path will lead you to home and the other path will lead you to certain death. There are two guys. One is the truth teller and the other is the liar. The truth teller is the one who will always tell the honest thing and the liar always tells the lie. If you get to tell one question to each of the guys, what will it be?

The answer is " What will the other guy tell me the road to take?" The liar is going to say " Well i'm the liar so i'm going to say the other guy will tell you to take the way that will lead you to certain death." And which ever road each guy tells you, you take the opposite.