Riddle: You are traveling on the road to Mecca when you come across a fork. Two men are standing at the fork. One will always tell a lie, and the other will always tell the truth. You don't know which is which. What question can you ask either of them to still get the correct road?
Answer: Which way would the other man tell me to go? If you are confused, let me help. Let's say the right road was the correct one. If you asked the truth guy, he would say left. If you asked the lie guy, he would say left. So you just go the opposite.