I can't find it now because google is garbage these days but years ago I once ran across forum thread or blog post from a small business owner who semi-regularly received random bogus patent infringement and other claims with offers to settle matter out of court for thousands of dollars.

He had a lawyer but after burning through a lot of money with carefully-written objections, he decided to just start ignoring them altogether. Which generally worked. These lawyers (and their clients) were just trolling for easy cash and never actually wanted to go to court because their claims were bogus and they would almost certainly lose.

Sometimes, however, the other party's law firm would call him on the phone to follow with their demands. He would let them yammer on for a few minutes, ask some innocent questions, and then finally interrupt them with something like this. "Here is what I have to say to your client's claim... you have a pen and paper ready? I need you to write this down. Okay, good. Here it is: 'Fuck you.' No wait, I'm not done yet. Just let me speak. I want you to also add, 'and go to hell" please. That is my official legal response. Have a nice day." And slammed the phone down.

Take the story with a grain of salt, but he said it worked 100% of the time.