I use the horn for this. For example, if someone cuts in front of me, I use Morse code to communicate the phrase "I am attempting to exercise empathy by putting myself in your shoes, and to be maximally charitable I am assuming that you're probably in a hurry, quite likely for a very good reason, such as perhaps your wife is going into labor, or you're running late for a big meeting, or your father in on his deathbed and you need to say goodbye to him for the last time, so I don't begrudge you for cutting me off, quite the contrary in fact, I wish you the best on your journey through life."
They then often use their horn to communicate something back to me, but sadly I'm not yet good enough at decoding Morse code to understand what they're trying to say.