I had someone ask me where we were yesterday as well (not at a control). My spur of the moment reply was one that I find satisfying: without stopping, I made a broad gesture with my thumb and said "We're on this hillside". Someone who is looking for detailed information in order to find a control would find this useless, while someone seriously lost and just trying rescue himself would find it very helpful. Not sure where in the spectrum this person fell. The truth was that it was all the information that I had, since I had just crossed a vague flat area and was planning to attack from the top of the hill.