Watch some games this week, specifically Cavs/Warriors/Rockets/Thunder so that you can add tidbits without having real knowledge. (Client A says Westbrook should be MVP you can cite some crazy play he made the other night.)

Look up the top scorers, rebounds, and assist guys. Also memorize the top 5-10 MVP frontrunners. If you're hardcore go to their Wikipedia pages and learn about them. This season you could get by talking about the NBA with just Westbrook, Harden, Curry, Durant, and Lebron.

Pick the Cavs to win the title and use the reasoning that Bogut was the best defender against Lebron and he isn't with GSW anymore. They might disagree, but it shows you know something about defense and matchups.

Watch a couple 30 for 30s to learn some cool historical shit.

Browse this Subreddit... you'll see a ton of the same things being discussed over and over. Your clients will likely be discussing similar topics.

Don't act like a know it all. Clients always want to look smart regardless of the discussion. If they give an opinion try and agree with them and support it with something you learned if you can. Ass kissing wins!