Related reference
John had found that neutral was the best tone when talking with Patricia. If you spoke with any emotional inflection, she would frequently deride what you said, though with a pasted-on smile or chuckle. Or she would take the antonymic tone or mood that you expressed, or the converse thought or opinion. And there were several instances where she reversed previous opinions, having lost track of them.
Soon after knowing her, John began to watch what he said around her, and how he said it, for she enjoyed baiting and goading him and other coworkers. He tried to respond as colorlessly as possible. A noncommittal "Hmm," worked well, especially because it frustrated her.