Question:
Prepare a complete tutorial, including an analogy to describe the mechanics and a graphic to support your analogy, on one of the subsequent areas:
Buffer overflows
SQL injection
Cross-Site scripting
DoS attacks
Injection attacks
Poisoning attacks
Suppose that your audience probably isn't up to speed on how any of these work. In fact, you can want to test your tutorial on a 'casual' user (parent? teenager?) to see if they will understand what the problem is.