The thing that drives me nuts is when I (the boss) is still working and the employees are standing around waiting for me to finish. It's like if I don't tell them to do something they can't figure out there is more work to be done...WTF.
Another is chewing up vinyl siding with a weed eater or forgetting to drop the deck b4 mowing.
My best is I hit a water spigot that was real low to the ground and hidden by weeds. The water line busted and his finished basement flooded. Thank goodness for insurance.