Riddle: There are two doors. One door lead to Heaven, while the other leads to Hell. A parrot stands in front of each door. One parrot always tells a lie, while the other always tells the truth. You do not know which parrot or door is which. You are allowed to only ask one question. So, what one question must you ask to determine which door is which, so you can finally go to Heaven? (Hint: The question involves what one parrot would say about the doors.)
Answer: It doesn't matter which parrot you ask the question to, but the question would be, "What door would the other parrot say is Heaven?". Then you would choose the other door.