"You have to consider that Reagan was twenty years older than I was. He was the age of my mother. So there was a generation gap. During one of our talks, he tried to lecture me and moralize. I said to him, "Mr. President, you are not my teacher, and I am not your student. You are not a prosecutor, and I am not a defendant. So let's not subject each other to lectures. Let's talk frankly and address the issues. If you want to lecture, we might as well wrap it up, because there's really nothing to talk about." He got a little upset. Not long after that, he said, "Why don't we go on a first-name basis? You call me Ron and I'll call you Mikhail." That was an important step."
January 1, 1970
https://en.wikiquote.org/wiki/Mikhail_Gorbachev