Daniel Cox was photographing polar bears near Churchill (Manitoba, Canada) when he witnessed a frozen $10k Nikon 600mm f/4 lens falling from 12-14 feet (4 meters) to the frozen tundra. The lens basically broke in half. Read the whole story on his website;
"One of our guests got so excited one afternoon she dropped her lens from the buggy. It wasn’t pretty. Her lens of choice was a Nikkor 600mm F/4 and it fell 12-14 feet onto the frozen tundra, breaking completely in half. She was an amazing sport and shared her grief by mugging for the camera. Of course I did not request the photo until well after the accident and the shock had worn off. Thankfully it was insured but it’s never easy to see a $10,000US lens get destroyed."