Since you were unhooking the TT at the time I'm assuming, and hoping, that alcohol was not involved. But, most of my falls have alcohol in the story somewhere.
At my favorite park they used to have installed charcoal grills; as many parks around here do. But, for some reason when they put these grills in they put them right at ground level and cemented them in. And, because they were right on the ground they quickly rusted out. After tripping over them many times in the dark I decided to take action (They were painted black, hard to see, and in weird locations.) One time I took a photo of my bruised and bloodied shin and gave it to the park rangers. Along with pointing out that the things had never worked very well, nobody used them, and they were rusted out. After bugging them about it for awhile they did finally remove them. It took a couple of years (it's a county park and you know how fast government operates) But, now there finally gone and everybody that frequents that park thanked me for pushing to get rid of the dangerous things.