There are 2 doors one leads to an exit and the other leads to a dead end. Guarding them are 2 robots on tells the truth and one tells the lies. You can only ask one of them one question to try and find out which door to go through you don't know which robot is which. What do you ask?

This is one of the oldest questions, all over the internet. http://www.google.com/url?sa=t&rct=j...6CLLOFqJOgsjeg

Same as the movie "Labyrinth" except the doors were guarded by creepy puppets