Riddle: There are 2 doors behind one is treasure and behind the other are lions waiting to rip you apart. In front of one door is a knight and in front of another door is a knave. The knight will never lie and the knave will only lie. They both know what's behind each door. You can ask them either one question or ask them to do one thing. What do you ask them or tell them so that you can get to the treasure?
Answer: "If you don't lie, point to the door that leads to the lions." They will both point to door of lions since the knave always lies.