A lot of people aim to write Flash Fiction because they think it’s going to be quicker than writing a longer story. Don’t they know their Blaise Pascal? (“”I have made this letter longer than usual because I lack the time to make it shorter.”)
It is possible to write a good story in 55 words (the title isn’t part of the word-count, but must not exceed seven words), but it’s not necessarily a quick thing.
Still, Saturdays tend to have more ‘running around’ time than ‘sitting at a desk time’ for many of us, and that might equal ‘thinking time’ if we’re lucky.
So grab your idea right now. Then, while you’re folding laundry, or taking the kids to soccer, think about how you can deliver a punch in 55 words. Think about which elements of your story you can strip away to cut it down to 55 words. What is essential in your story?