I called party games for drunk people only, then my brother in law made us play Codenames 9 times in one weekend at the lake | Board Game Geeks - Thought Shares
Oh man my buddy had the exact same thing happen at his family reunion last summer. His wife's cousin brought out Codenames and they played it like 6 rounds back to back and he was dying inside by round 3. The worst part was everyone kept taking it so serious, like arguing over clues for 20 minutes while he just wanted to go float in the lake. He said the "spy" clues got real bad after everyone had a few drinks and one guy kept saying the same word over and over. Your brother in law sounds like the type who thinks a game night is a personality trait.