haha dude i dont think anyone can answer that but you.
i do crime fiction, and i have a story prepared from an assessment task we did previously. whatever you are doing, i bet you'll be cramming it up something shocking tonight.
find out from your teacher today if possible what kind of question it will be - creative writing or just a creative response. we know ours is creative writing because we havent been prepared for anything else. if they havent prepared you for anything other than a creative writing story, then you'd better get cracking on one.
good luck mate