The worst thing I ever hit was an old telephone pole guy wire with my brush hog. One end was still anchored into the ground. Wrapped it up good, sucked the deck down on top of it and stalled my tractor. Getting it free and unwinding it all was quite the chore.
I also hit a "fresh pile" with my trimmer once...got it all over the left side of my shirt and a little in my mouth too. Now I can truly say with confidence when something tastes like dog sh**! Glad I keep a spare shirt in my truck at all times.