Worst move ever, All opponents out (some number) rounds laughing,
Then he explained it and showed up. We had just killed one of the Dragon Lords ! So much lower level characters, first time encountering a dragon (much less a dragon lord), etc. It was flat out crazy!
Apparently we weren't supposed to be able to kill him (duh), as he was so much more powerful than we could imagine, but he was statted as an encounter, not as an event, so the GM went with the rules and adventure as written.
As a side note, that particular character retired, built himself an inn, and had the pieces of the boomerang mounted for everyone to see.