You bring up a good point which is not exclusive only to women. People moving to the United States rarely know anything about football. (Not being born in the US, I had to Google to find out who John Elway is, but I understood from your comment that he was a football player).

It's a very common culture of exclusionism, but, I've observed both in the US and Europe that it's pretty much only guys who participate in it. I've only ever had a woman say "you don't know who X is?" to me in jest. And then she would always explain afterwards.