EarnIn Data Scientist interview questions

Phone call with hiring manager, then an onsite with 4 people including the hiring manager, a data scientist, the head of analytics, and the CEO. Everything went fine except the round with DS who was sort of unprofessional. So I told the DS that I know my friend was interviewing for another DS position, then two questions into the interview he asked if my friend shared the questions with me. Quickly he realized that he hadn't even interviewed my friend yet. I was kind of shocked to hear that. But I probably shouldn't mention my friend at all.