personally i would never be mean verbally in any way to anyone. too easy for it to be perceived as a criminal threat.
You can do what Britt McHenry did to the desk-chick of the company that towed her car in Virginia. And by towed, I mean likely stole, since the particular firm has quite a reputation.
Be very personally insulting while only threatening to own the people in court, no physical threats. I don’t condone what she said, but I can understand why she was extremely pissed off.