I'm stumped when 5 interviewers in a row ask that question, and at a company like Google. Given that I have enough friends there that I have some sense of what the culture is like a priori. Asking the same question or variant thereof is painful :(
Ask a question about the interviewer's workday! A few years back I asked a stakeholder in a one-on-one interview to describe some of the issues he was hoping I could help with. Soon enough we wound up in his office going over his existing systems while I extemporized some solutions. Got the job, too.