Backlash by Aaron AllstonBacklash by Aaron Allston. It is indeed a Star Wars book.
At its summit, he offered the note to Kaminne and Tasander. They and some of the subchiefs gathered around could read, and news of the note’s contents spread throughout the camp.
Kaminne pondered. “What’s an elegant way to say No, and we hope you die in misery?”
Tasander shrugged. “My father used to say, May the stinging insects of a thousand worlds seek out your moist places.”