They knew who she is. they just clarified to avoid confusion. We associate things by contexts. If you were talking about history or civil rights, your mate would most likely have confidently known who Rosa Parks is. xkcd.com/1053/ When confronted or put under pressure we tend to question everything. You think the name is funny. He doesn’t. So obviousltly his understanding must be wrong. Its not “civil rights” + “porn”, there must be something else he is missing. It can’t be the obvious thing he is thinking about because that isn’t funny …