as you are working on the golf ball riddle throw this one in.
Unless you know this one its pretty difficult:
You walk up to a mountain that has two paths. One leads to the other side of the mountain, and the other will get you lost forever. Two twins know the path that leads to the other side. You can ask only one question, but you can ask them both that question. One lies and one tells the truth, and you don't know which is which. In order to guarantee you go down the safe path what do you ask? (you must explain your answer)