Riddle: There are two doors. The door on the right leads to freedom and the door on the left leads to a room full of lions, but you don't know which one is which. There are two guards. One always tells the truth and one always tells a lie, but you don't know which guard is which either. What will you ask both of the guards to know which door leads to freedom?
Answer: Ask the guards what would the other guard say if you asked which leads to freedom. Then pick the opposite door. - Explanation: The guard that tells the truth would have to tell the truth so they would say what the other one would say, the door on the left. The guard that tells a lie would have to tell a lie so they would also say the door on the left. You would pick the oppisite door because you know one guard always tells the truth and you asked what the other guard would say and they both said the same answer, the wrong one.