Especially to middle school boys, story plot maps can be boring. But using this metaphor of the plot line will grab their attention and get them more engaged. A short story is just like a pimple. Things start to get sore under the surface. Then the pimple grows bigger and bigger as it gets more and more irritated. Then it pops! Then the healing begins and the swelling goes down and the skin calms and gets back to normal... but there may be scars. It fits so well. While it is a gross analogy, they aren't going to forget it.