Sunday prompts may be fun or difficult, they may work specific "muscles" or just let you play. They may be precisely defined or widely open ended, meticulously timed or totally casual, and they may involve a long paragraph of complex rules to follow or a few words meant to inspire...anything. These are a few I've found over the years that have been fun, funny, challenging, interesting, or generated some good writing.
Don't worry if this doesn't lead to your next short story for the New Yorker or The Atlantic. I don't know why writers have this thing where everything they write has to be headed towards publication and nothing is ever abandoned or just played with for fun. Go have fun and play with some words! Frolic with them. Everything is always something a writer is "working on." Why is nothing ever something they're "playing with"? If you start to see something "real" in a prompt response, that's great, but it really is okay to write something that you absolutely never intend to publish. This is not a waste of spirit or words.
Musicians train for years, practice, and rehearse long before any performance. Actors practice and rehearse and most without nepotism train for years as well. Visual artists train for years, and draw or doodle constantly when they're not painting things and most of their work sits in their studios unpurchased. Dancers train for years, practice, and rehearse. Architects study for nearly a decade before they design so much as a house. Film makers train, rehearse, and most of their work ends up on the cutting room floor. Most of what fundamentally goes into the creation of a work of art happened before the "performance" even began. That's why it's so impressive. You're not just looking at thousands of hours of effort--you're looking at thousands of hours of effort after tens of thousands of hours of training. Just because a writer's "practice" sits on a page and doesn't go away (except after many years) doesn't mean it shouldn't. The audio/visual arts disburse in waves across the universe and if they don't hit eyes and ears they are lost forever, but the permanency of words on a page doesn't mean you have any obligation to them. Just have some fun and see what happens.
There is absolutely no reason to expect that everything you write will lead to a finished product, and honestly, there's every reason to expect that it won't. If anything, the idea that your every written word is just a revision away from being worthy of publication is hubris beyond measure (said the blogger). And the sentiment I've seen among some writers that nothing is worth putting effort into that won't one day be published is a very stifling way to approach art. Writers have "jam sessions." Writers have "doodling." Writers "sing along with the radio." It just involves writing, so it looks a little different. But if you let go of that expectation, you can actually forget the writer's block, forget the expectation, forget that internal voice that has something to say about it's "potential," forget all that horrible presumption that leads you to stare at a blank page because it HAS to be brilliant from the very first word, forget it all, lean back, and enjoy playing.
Lastly, it seems like sometimes writers get really worried that everything that comes out of the same prompt will be similar and feel derivative, and that if for some reason one of these prompts somehow DID lead to something to be published and submitted, there would be dozens, perhaps hundreds of "clones" out there competing for those publication opportunities. Trust me, it won't happen. Trust me. Truuuuuuuuuuuuust me. I sat in class after class of an undergraduate creative writing program, 75% of which consisted of ardent Stephen King fans who watched more TV than they ever read, and week after week, prompt after prompt not one of us--not ONE of us--generated something that was even remotely like the others. If your writing is derivative, that's one thing, but it won't be the prompt's fault. Between your angle and take, your style, your focus, and the evolution the piece might take there is virtually no chance that two pieces published off of the same prompt would ever be recognizable as such without the authors divulging that fact. And in point of fact, I know a few published pieces out there (nothing like each other, I might add) in which this is exactly the case. Shhhhhhh.
Relax. Have fun. Remember why you fell in love with writing in the first place, and do it all over again. This is miniature golf and pizza for date night, not the 10th anniversary dinner. Beside, you might just find (like with golf and pizza dates) that the best moments come when you're least expecting them...