This happened to me when I got my MJ Stam - a friend's mum was like "OMG that's so gorgeous! I want to see how it looks on me!" and proceeded to take it out of my hands, try it on and preen in front of her mirror. I just stood there while she swung it from side to side, picked it up by the chain and hung it over her shoulder (I never use the chain, as I carry a lot in my bags and I thought the chain might snap) and scrape her nails all over it. By the time she called in her youngest daughter (aged 8) to "have a go," I thought I was going to have a stroke!
I don't think I could have even let it get that far! There is no way I'd be letting a kid play with my bag!