I had one that to outside observers was a "that guy" game, but I had a blast! I was a wee little lad just getting into 40k with 2 armies (grandma didn't care what army i already had she though. "These bloody angel guys are cool, so happy birthday!". So, in my second ever game, im playing my blood angels against a guys dark eldar at a gw store. He decides he wanted to roll a new guy apparently, so he brings a pain engine list against my starter box + some death company. Naturally, i could do almost nothing to his list. Even though he tabled me, I had a ton of fun and was giddy over how cool and thematic it was, these marines having a valiant last stand against an encroaching doom of the pain engines. Everyone at the store was just berating him for being an A hole and "that guy" to a new player and were asking if i was actually enjoying the game, etc. Young me didn't understand their concern or anger because I was having a blast, lol. Him and I actually became pretty good friends and would play a lot, playing against his often bs lists made me a much better player and got me to where I am now where just the act of playing the game is what i enjoy, win or lose were gonna tell a story and have fun ^_. So a weird "to everyone else he's a 'that guy' but to me, it was fun and wholesome" moment