I had my 70-200 2.8L mounted to my DSLR , on my tripod, and forgot to lock one of the legs. The whole thing toppled over into dirt. It was on the banks of the Bow River in Canmore.
the elk were crossing the river and I was in a hurry. " Many harsh words were spoken" !!!
Thankfully there was no damage done and only a very small scuff.
As for changing a lens, mine are very expensive so I take the extra second and use both hands. I really don't care if I look like a PRO or not. I mean they are covered by insurance ... but really who ya trying to impress.
I was to the left of this shot. You can imagine how upset I would have been had it happened on the side close to the river.