I found that simply asking questions to learn about
them ( as well as the person I'm speaking to) is enough.
This is something that 99% of "nerds" don't understand about sports. You don't have to fake your way through "knowing about sports" to have a conversation around it.
Suppose you're in Buffalo, NY and you don't know a thing about sports. However, unless visiting with your eyes and ears closed, it would be difficult not to see that the city is really into its football team.
If you are "stuck" in a conversation with a Bills fan and don't know a thing about football, you could just ask - are the Bills good this year? what's it like being a Bills fan? are Bills fans as crazy as they say? how did you come to be a Bills fan - were your parents Bills fans?
There's like 100 possible conversation angles there that don't require any knowledge of sports
Discussions like these show that some people really block out anything beyond their specific interests.
I don't care about superhero movies, so I haven't seen any of the Marvel or DC movies, yet I still know they exist and sometimes I know which one is being promoted right now. If I got stuck at a table somewhere with someone who is a big fan of them, we could have a conversation. It'd mostly consist of me asking questions, but that'd work fine, because as a fan he'd have opinions to share. Same thing with sports or anything, really.
Right! It's so simple to me, that I actually get kind of frustrated with people who haven't figured this out.