Hit a Coast Guard cutter
Last summer I was motoring H320 over to Riverwalk Landing in Yorktown, Virginia, to pick up a client who was joining five guys. As I entered the marina, I misread the wicked current and wound up sliding into a Coast Guard training vessel that was parked. The young men in training were awestruck and useless until the elderly dockmaster ordered them to fend off. My starboard beam smashed into his bow, ripping out the stanchion and doing some fiberglass damage. The CG boat was bulletproof, not so much as a nick.
We got free and tied off, awaiting our friend. Being guys, no one talked about it and we sailed away. Two hours later two Coast Guard boats came after us with blue lights blazing. "Prepare to board!" They had forgotten to do the paperwork. Later their commander called me to see if I was going to file a claim against the government for the damage. Of course not, since it was totally my fault.