My freshman year of college, I went to the first football game of the season with my hall and our brother dorm (#littlelibertythings).
After listening to one of the guys behind me loudly complaining about how much our kicker sucked for a quarter or two, I couldn't handle the secondhand embarrassment anymore, turned around, and explained squib kicks to him. Three of the guys sitting with him asked for my number, and he never spoke to me again, I don't think.
Why do I tell you this? To remind you that football knowledge is the key to getting dates!
Just kidding. (Guys like it when girls know about sports. Guys do not like it when girls know more about sports than them.)
Why do I tell you this? To remind you that the most annoying part of any sport is the spectator trying to act like they know what they're talking about!
As a rule of thumb, the knowledge you have of the game and the amount you talk should be directly related.
Unlike writing essays in undergrad, if you're attempting to fake your way through a sport, the worst thing you can possibly do is try to stretch the few facts you know into paragraphs of commentary.
This is especially true for lesser-known sports, like lacrosse; or highly specialized sports like hockey or baseball, where the terminology and statistics are super specific to that game. But remember that if the bar for basic knowledge is lower (as with football or basketball in the states), then so too is the bar for advanced knowledge — the slang, surrounding stories and details of the sport. More people will know particulars, and it's best if you, a fledgling fan, avoid jumping in too deep.
For those trying to learn a sport (or fake it, at least), my top recommendation (besides, you know, just learning it) is to stay quiet, match the emotion and volume of those around you, and chime in only once you're 100% confident you know what you're talking about.
I purposefully picked a baseball photo to accompany this post, for example, because I know next to nothing about baseball. It's amazing, really, considering how much baseball I've watched in my time; but it's just never caught on with me the way other sports have.
So when I go to a baseball game, guess what I do?
I sit there and watch the baseball game.
I do not offer my thoughts or opinions on the game, because I know nothing and therefore my thoughts and opinions do not matter. I listen to others around me marvel at the pitcher having thrown nothing but sliders for the last three innings. I nod in agreement when they groan about a runner being too far off base. If People Who Know say we need a double play ball, then heck yes, we need a double play ball! Me and my sunflower seeds second that motion!
Fans of a sport know their sport, and they can tell when someone doesn't. So do yourself a favor, aspiring fans, unless you want to annoy everyone: If you don't know what you're talking about, don't talk.