DS8 was REALLY into NASCAR when he was 3 or 4yo. He cared not only about who drove what car, what the number of the car was and what color it was for every driver, but he also knew their sponsors and many stats about their performance. This was particularly odd because neither DH nor I could have named 3 drivers before DS got into it.
The funniest moment was when DS asked me what Viagra was because it was a sponsor for Mark Martin's car. I thought for a moment and said "A medicine for men," which seemed to be enough for him. (Thank goodness!)
He enjoyed many lengthy, serious conversations with adult NASCAR fans, who usually found that DS knew more than they did about the subject. Happily they usually seemed to appreciate him. We never had any bad experiences with these conversations. The adults sometimes seemed a little awestruck that such a little boy knew so much about the sport, but they were always kind to him and treated DS with respect, even as a peer.
I was always rather glad that his topic of choice then was one that was more or less readily accepted by society...