Clueless Non-Gamer (?) wondering about social perception of popular video games?

Hi everyone, I really hope this is the right sub! So I've never played a video game in my life, while my boyfriend is an avid gamer. I'm currently at wits end because he's constantly making gaming jokes that I don't understand - which he thinks is hilarious so he refuses to teach me anything. For example, an hour ago, while he was playing a game called Dota 2, I was telling him about me standing up to my rude prof. He said to me: "lol that's dark what are you, a closeted league player?"

I have no idea what that means and when I asked for clarification, him and his buddies just laughed on discord and they'r e still making jokes and laughing at my expense. I love them all but I am so frustrated and would love to show them up with some jokes of my own. Can anyone explain what connotation is behind today's popular games - for ex. Dota, R6, "league", COD, GTA, pub G, minecraft (maybe? I'm not sure if this one is less popular for guys in their 20s), and NHL. Which ones are popular, which ones appeal to most people, etc. I think it would be great fun to join my BF in his games and I have a good feeling some knowledge on this matter would help in him taking me more seriously lol. Bonus points if you guys have any recommendations for video game Christmas gifts for obnoxious hockey players!