Forgot my wallet at home - not a big deal really, DW just got to pay for everything however I got nervous every time I same a LEO - which was 5x's more often than usual.
Forgot the pipe I use to tighten the WDH... on the back bumper! I was surprised to see it still there 60 miles later.
Left same pipe on same bumper after disconnecting late at a KOA. As I slowly moved the TV, it fell off the bumper and rolled, bounced, and flipped downhill on the campground lane for about 200 feet. 24 inches of steel pipe makes a heck of a racket after quiet time! (DW got the pipe while I finished parking, very neatly, over top of our subterranean fire ring- just glad I did not put a wheel into it.)
About a month later I was behind an F250 at a traffic light. I laid on the horn since the driver had left a 5 lb. sledge hammer on his rear bumper. He got out, got the hammer and thanked me. "That would have been dangerous when it fell off" he said. I figured it would not have fallen off - unless I didn't warn him about it.
And finally - last week - forgot to close the hitch on our utility trailer. The chains caught it leaving the driveway, no damage. First time I have ever not done a final walk around, first time I ever forgot the latch.
I'm sorry, what was the question again?