I've been a sports dilettante on and off throughout my life. I didn't really get into it early on. I played soccer, but wasn't terribly good at it; mainly I remember A) my last two coaches looked like Robert Klein and Tom Clancy and B) one of our practice fields in Vienna, VA was in a park where Robert Hanssen would later leave secrets for the Russians. And the less said about my abortive high school track career, the better (I think I mainly got into it because my brother did it and because the first girl I'd ever had a crush on, Nicka, got into track). And I only barely covered sports for my high school paper and at the Hermiston Herald, so I didn't get immersed in it that way. (I like the story Stephen King tells of getting a job as a sports columnist when he was in high school. King told his new editor that he knew little about sports. The editor said "These are games people understand when they're watching them drunk in bars. You'll learn if you try.")
I now follow the NFL and college football, and am starting to follow the NBA again, which I haven't really done since the mid-90s (the last time the Portland Trail Blazers were consistently good). It's like I'm studying: one of the neat things about watching the Super Bowl on a big screen in 2002 was getting a better sense of the patterns in the plays, for instance.
I can even remember one joke. I was watching pre-season basketball several years ago and a player threw a ball wild, going nowhere near any players and getting caught by someone in the stands. I said, "Yeah, you can have a sixth man, you just can't throw to him." I got a laugh.
I only knew the one meaning of sixth man, the "fan influence" meaning. Turns out there are several. Shoot. OK, think more on this, Chris! Learn more and you'll get a second sports joke!