On the platform at the Harvard T station, a man was singing and strumming a jaunty version of “Hotel California.” He had a harmonica strapped to his face, and was pumping his feet to beat a drum and make a small dog puppet move back and forth as he played.

A woman with straggly gray hair went over to him. At first I thought she was complimenting him or asking him a question, but then he started saying, “Go away, go away.” He interrupted his guitar playing a few times to gesture for her to leave, but she started yelling louder and getting in his face.

I went over. She was yelling that he was breaking her eardrums and he needed to shut up and be quiet. He told her to move away. She gave him both middle fingers, stuck them right in front of his face. I asked if she was getting on the train, which had just arrived. Then she started cursing at me and giving me the middle finger. I asked again if she wanted to get on the train with me and she told me to F off and shut the hell up. She started yelling again about her eardrums. The singer kept telling her to move away if she didn’t want to hear. I also asked if she would walk down to the end of the platform, but she kept yelling and cursing at both of us and sticking her middle fingers in our faces. I realized the train was about to leave and ran into the nearest car just as the doors were closing.

As the train pulled away, I thought about what I could have done instead. I remembered that as a bystander, you’re supposed to go up to the person who’s not making a scene, and casually talk to them. You’re not supposed to confront the angry person. I knew that, but hadn’t done it — these things always feel different when they’re real. Anyway, I didn’t think the man was in any danger or that he couldn’t handle the situation on his own. I didn’t help, but I don’t think I caused any harm either.

Later that day, I saw the same woman walking across Boston Common by herself. I couldn’t hear what she was saying, but she was still yelling and cursing as she walked through the park alone.