this should be OBVIOUS ....BUT... I know a guy who tied off his safety harness to his truck while roofing. (Didn't bring the ground anchor and no trees) Another guy in the crew jumped in said truck and went to the store for more roofing nails. I shouldn't need to say the end result.
Moral of the story, make sure the keys are in the hammockers pocket. Nothing worse than being dragged down the lawn for a bit if someone isn't paying attention.
Otherwise, great backwoods engineering!
"It's better to keep your mouth shut and let people THINK your stupid than to open it and PROVE it" - SFC Kagawa, United States Army (my old platoon SGT)
*Originally -Abraham Lincoln 16th president of US (1809 -1865)