I usually just explain what I'm doing. If I'm with someone else, I generally don't get asked what I'm doing, though. We just have a conversation that covers it up. Last week I was walking in the city alone, and I had someone approach me and ask what I was looking for because maybe he could help me find it. It was said rather suggestively. I smiled and pretended my gpsr was a camera (it does look like one!) and just kept taking "pictures." "Nope, just sight seeing." I wonder of men and women caching by themselves, which attracts more questions?