How can I explain what SQL injection is to a Non-Techie?
Here, if you have a milkshake, and I have a milkshake, and I have a straw. There it is, that's a straw, you see? Watch it. Now, my straw reaches acroooooooss the room and starts to drink your milkshake. I... drink... your... milkshake!
Mario Giambanco
Director of User Experience Development
XKCD does a good job of it.