Strange but quite harmless

What do you say to the woman giving you sideways glances at the fruit stall in Waitrose when you start taking pictures of bananas? I told her, "it's okay, I just thought they looked interesting", which probably only confirmed her initial thoughts.
You can't really start explaining blipfoto can you? "Well there's this web site see - and I must take a picture every day - It's a kind of bl... oh sod it".
But I must think about what to say in future and at least be witty - I'd prefer it if strangers didn't think I was strange.
Anyhow, they did look a lot more interesting than this. They were very green... but I guess you had to be there.