I had my wallet stolen once. I had it in my backpack when I got out of the cab at the train station, and in the short walk to the train, the thief had popped the buckle, untied the drawstring, pulled open the backpack, unzipped the inside pocket and took out the wallet. All without my knowing. I had about $100 in there, luckily nothing else (I was travelling).
I was pretty pissed, but I have to say, that's one skillful thief.