I've got a good one!
Had to get a mates car to the workshop, so rented a car trailer, and hooked it up to a mate's VT SS. Put the car on the trailer myself as engine was stuffed.
Anyway only had one strap and fitted that to the car thinking that it won't roll back if I strap it to the front of the trailer. Kept the winch hooked up too.
Well, got 40 metres down the road to a speed hump, braked for speed hump, heard a loud crunch, so I pulled to the side and stopped.
The car had moved forward and the front wheels were over the front of the trailer, with the front bar pushed into the winch upright.
I was so pissed of with myself, got the jack out and had to jack under the tow bar to lift the front of the trailer back up then had to go get the texi basher VN v6 out, hooked it up to the back of the car on the trailer and yanked it off the winch, and back to where it was supposed to be.
Finally sorted the car out, got another strap for the back then got going, felt a bit weird and after 100 metres could smell/hear something was dragging. So pulled over again and found that in my rush left the jockey wheel down! The rubber wheel was mangled, so put the jockey wheel away and got going again. Made it to workshop.
So I ended up bending the front bar, number plate and reo bar on his R31. I always strap a vehicle down properly, but just this once I didn't, don't rush these things, is all I can say!