Write your own 100 word story
Surely you've got time to write a 100 word story.
Write one that relates to the week's theme - in this case, Day Job. It can mention it explicitly or just have the same kind of feel. Make it have a beginning, middle (conflict), and end (or at least suggestion of resolution). Then see exactly what you've got to do to get your story up as part of the weekly challenge.
Then do it again. It's good practice.