A fan quiz is a listening task with the motivation built in: students who know the subject want to answer, and students who do not want to see whether they can work it out anyway. Either way the class is listening for specific details rather than gist.
Keep the questions spoken and the answers immediate, then turn the format round: let students write five questions about someone they know a lot about and run the quiz on each other. Writing a good question is harder English than answering one, which is where most of the learning in this activity actually happens.