I've read the few sad tales on here about people dropping their lenses and wondered if it would ever happen to me.
Well now I know what it's like because it has.
We went away overnight to our daughter's house a few hundred miles away so I put all my gear in my camera backpack. Coming home we stopped to take some pics and I had to change lenses so I opened the bag, switched, and DIDN'T JIP THE BAG BACK UP. Once home I grabbed the bag, dragged it out of the flat back area ( Prius ) in our cement floored garage and clunk. My favorite lens, 70-200 2.8 IS fell onto the floor.
I guess the Gods were smiling on me as when it fell ( I watched it ) it landed on the plastic lens cover on the mount end. All seems well with it though. It focuses as it did before, and the IS still appears to work correctly. In fact I can't even see a mark on the plastic cover.
Hopefully this has been a cheap lesson to me to be more careful.