It's amazing the range of responses people of all ages, shapes and sizes get, as does different places, and the times we choose to conduct our hobby.
At times I feel like the Pied Piper, with children swarming to find what I'm digging up, sometimes the solitary soul shutting out society, sweeping remote places alone, and other times the nerd, or the object of some Muppet's wit.
I have told many people the following when they ask me what I'm doing:
I'm in bomb disposals
Told tourists that this machine measures seismic activity, and it looks like there's a big one coming!
I've told people that I lost my virginity on this beach and I'm trying to find it
But.... beep beep beep, for me is so lame, so inaccurate and obviously very un original, "let me guess, your a pedestrian crossing", or, "jeez your funny, are you a clown".
I have to say nearly every person that approaches me is genuinely interested, and I respond likewise, and those who don't haven't a clue how much I enjoy what I do, so I usually do what ever it takes for them to continue on so that I can.
Cheers
Bazza