Once, punching my boss in the solar plexus after he shoved and threatened me. There were witnesses, so no charges, but I still got the sack.

Second time, I was in a QA job and wouldn’t wave defective units through. I came back a few days later and sandpapered the front window of the car of the lying shit who fired me. I also called the responsible federal regulator to report the fraud but they took no action.