Well, not exactly overboard, but....
On the way back from a camping trip a few years back, I set my main tackle box on top of the pop-up camper after we put it down for the return home. It was one of those big plastic boxes with 4 or 5 3700 size plastic bins as well as other holders, almost all of my lures, crankbaits, spinners, etc.
You guessed it, pulled away from the campground, drove about 30-40 miles before terror gripped me...I forgot to take the box off the top of the pop-up. Not sure why I didn't see it in the mirrors, whatever the case, we drove back, retraced our drive, no box. Several hundred dollars of fishing lures gone forever.
Some fisherman got lucky that day.