In order to prepare for this exam, I spent the better part of my past week or so listening to lectures recorded when I audited Dr. John Thompson's Presbyterian Creeds course two years ago. During one lecture on the atonement, he shared this story to illustrate the concept of the Christus Victor theory of the atonement. I'm paraphrasing here on the basis of a verbal permission from Dr. Thompson to do so (given during the course, also recorded) provided I mention where I got it. (I wish I had the illustrations he had, but I'll try to make do with words)
The Saga of Fifi
You are the proud owner of a poodle named Fifi. Fifi is a wonderful little dog, but not especially obedient. When you take her with you on a fishing trip, she just won't follow your instructions.
"Sit, Fifi! Stay put, Fifi! Don't go near the side of the boat, Fifi!"
Needless to say, Fifi does wander too close to the side of the boat, and falls off. But as Fifi does her pathetic effort at a dogpaddle, it gets worse!
A shark appears, and sees Fifi alone in the water, and goes after her. Fifi is doomed!
Thankfully, all is not lost, for you remembered to bring lunch! You have a nice, tasty, chicken in your boat, and you toss it overboard, assured that the shark will consider this fresh, juicy, meaty chicken a far more appetizing treat than scrawny little Fifi. The shark takes the bait, releases Fifi, and goes after the chicken. Fifi is saved!
But not only that, but this is no ordinary chicken. This is really Super Chicken in disguise. Super Chicken breaks the shark's jaw, and restores Fifi to perfect health as a bonus. All is well with the world again.