It was a bright and sunny day. Which, all in all, was a terrible way to begin a story. But Snoopy was determined to begin his Great American Novel, whether the day was bright and sunny or not. Of course, “write what you know” didn't have to always be taken literally; Tolstoy probably didn't know half as many people as he wrote into his books. If Snoopy was to write what he knew, the book would be about writing a book, which all in all would be rather dull once the thrill of recursion passed.
“It was pretty good, but also pretty bad.” As an opening line, it was okay, but nothing exceptional. “Everyone knows that rich dudes want to get married.” And everybody knew that if Snoopy was to write a love novel, he'd likely be sued by some dame convinced that it was about her. He'd smooched so many dames that he'd lost count of all the exact circumstances, so there was bound to be some repetition. “He was a young beagle who wrote alone on a typewriter and hadn't published a novel ever.” Now what had he said about writing what you know?
Starting the novel would be easier if he knew what exactly the novel was about. Snoopy was pretty sure that there should be a princess in there somewhere, even if she didn't know she was a princess. And you could never go wrong with ninjas. There should also be vultures; Snoopy had much experience in being a vulture, so he could provide vivid characterization. And maybe include some bears. Yeah, bears would be good. Within moments, Snoopy had typed out the first paragraph of his Great American Novel. He promptly went off to celebrate by quaffing a few root beers.
When he returned, he reread his intro. “There once was a ninja and a princess. The princess didn't know she was a princess; she only knew she was a prisoner to the evil vulture enclave. The ninja rescued her, though it took much effort and fighting of bears.” Hm. It was a solid introduction, but unfortunately there really wasn't much more he could add to improve it. The book would have illustrations, of course, but even then Snoopy felt it wouldn't fit the ideal page count.
He was in his den admiring his Jackson Pollock when it hit him. The story would begin with a splatter, a splatter on the wall. Then it would embroil itself into a mystery that would threaten the entire world, until the source of the splatter was revealed and all was set right. He hurried up to his typewriter and wrote the fateful words: “It was greenish-yellow, rather morbidly sticky, and splattered across the face of the Statue of Liberty's plaque. Where it came from, nobody knew, but it was proving to be devilishly hard to remove.” The story just went on from there, practically writing itself.
Snoopy had just about finished the entire novel when the Red Baron shot his typewriter into pieces, destroying all of his hard work. He learned an important lesson that day: never write the Great American Novel while piloting a Sopwith Camel.