I liked it. I suppose it's not a particularly shocking twist, but amusing enough and works well within the limits, and well written to boot.
Just one question: Does Elrond fall in too?
Author's response
The challenge here was to tell the story in 100 words. I figured if I edited out all the angst and fighting, it would work out nicely if Isildur just tossed the ring. As he was not inclined, Elrond needed to nudge him a bit. And, no, Elrond did not fall in. Although, maybe he should have.
:)