Have done a lot of dumb things in 30 years of camping from tents on up. It seems the most prevalent is forgetting to unhook the power cable when moving the MH or taking it out of the yard for service. Have never done it when going on a trip.
Had a 32' Cougar TT and were camping with a BUNCH of friends who all got there ahead of us and stood around watching as I made a perfect parking job. Got out, checked the level and put some blocks under the right wheels, set the chock blocks that go between the wheels, set the little jack pylon under the jack and proceeded to crank up the tongue. The tongue came off of the hitch very nicely and so got in the Excursion and moved it up a ways. As I was walking back to the trailer, the DW opened the door and got in the trailer and there was this big bang as the chock-a-block on the right side of the TT popped out and the trailer rolled off the blocks and not only dropped off the jack, but bent it to where it wouldn't raise or lower. I did carry a scissors jack and we were able to raise the TT enuff to hook it up and straighten it out. The chock flew about 30' thru the air and dropped right in front of a MH, but didn't hit it. Should have double checked the chocks and where the tires were on the block.