This is an old favorite of mine. I'm including a link below to a website that publishes stories of exactly 55 words. Read a few of them, and then you have one of two choices: a.) do a standard 250 word post discussing the stories followed by a 100 word response or b.) try writing a 55 word story of your own. The rules for a 55 word story: 1.) I will be checking to make sure it is exactly 55 words (otherwise, it wouldn't be a 55 word story), 2.) you can title it, but it doesn't count towards the 55 words, and 3.) there are no restrictions on content, but keep in mind this is a public forum, so exercise common sense. For the response, you have the option of responding to someone's story or writing a second 55 word story.
However you choose to go about it, have the first post up by Thursday night (09/29) and the response up by Sunday night (10/02).
The link: http://www.birdandmoon.com/55words/