It was a rather heated conversation, too. At first I thought she was talking to her boss or a co-worker, as she was complaining about how she had already applied for her vacation days for next year, and now all her plans were going to be disrupted. The more we listened, however, the more we realized that the person on the other end of the phone was not her boss, but her boyfriend. Apparently, he had agreed to be in a friend's wedding, which was going to disrupt whatever plans the woman had already made with him.
As we were getting off the train, she was still talking to him, using phrases such as "you should treat me like a partner" and "I can't do this anymore." It sounded as if she breaking up with her boyfriend on her cell phone, while riding a moderately crowded train. And we weren't the only ones on the train intrigued by her conversation.
As Nomi and I walked home, I pondered the advice that fiction writers often get to pay close attention to people's conversations, the better to write dialogue. The fact that this woman was having this conversation on her cell phone meant that on the one hand, we weren't getting the full dialogue. On the other hand, I doubt it's a conversation we would have heard at all if it had not been for the false sense of privacy afforded to her by the cell phone.
So here's an exercise for writers: listen to someone's cell phone conversation on the train or somewhere else public. Jot down what that person says, and then fill in the dialogue you missed on the other end of the phone call.