I think everyone's done some stupid stuff...we get distracted, or something like that, and voila! Instant mess.
For me, the dumbest thing I did was with our old tow vehicle, 1988 Suburban. We had bought a Rockwood and were enjoying the heck out of all the trips we made. In one campground, their sites are all in a "star" pattern so there are 5 sites, but at the back you get much more room than at the front. I was pulling in and started backing up the trailer. I stopped to examine a tree that was kind of leaning over to make sure I didn't scrape. I opened the back doors to the Suburban because I was going to pull out the boards/chocks, got back in, and backed up at a hard angle. Next thing I know, I got one of the doors smack in the front of the new fiberglass front on Rocky (the Rockwood). A nice big gash in it, luckily it never leaked.
Speaking of stupid, 2 years later, an older gentleman who had swerved for some reason rear ended the rig @ 70 mph while I was pulled over on the shoulder changing a flat. I was in the back of the trailer (rear bathroom, storage area) and narrowly avoided getting killed. The car tore right through that fiberglass and aluminum, missed my head by about 6 inches. I was upset at first but found out later he had his grandson in the vehicle and the struts/uprights went through the windshield and A-pillar striking the child in the head. :( I guess he recovered, thankfully.
That's how we lost our Rockwood, but we had replacement insurance on it so it didn't turn out too badly.
Too many stupid things to do in RV's, I'm constantly banging my thick head on the bedroom slide when I go to check the water heater (which is about 5 feet from the slide) :/