Kiss His Ass?

A few years ago, I was walking past a bus stop when an elderly man said hello to me. I DO NOT say hello to unknown men when I’m alone in public because I feel it opens the door for them to say anything they want to me, so I just walked past this man without responding. He stood up and yelled after me, “Fuck you bitch! Kiss my ass!” I was really embarrassed because everyone within earshot turned and looked at me as if I had really insulted this old man.