First off, little background on the two guys involved.
Our furry player was your standard quiet, nerdy guy. Skinny, usually wearing something terribly unfashionable, and kinda awkward. Great guy, though, and always had my back; I still remember him hauling my drunk ass away from the campus police, breaking into a locked closet to hide me, and then throwing them off the trail. Total bro, and great roleplayer.
Our second player was your usual "alpha male" type gamer; you know the type. Always needs to prove that they're the best thanks to being a bit nerdy in high school, and thus overcompensating by being an aggressive ass to anyone he saw as 'less' than himself. All right player, usually was the GM, and an okay person, barring the flaws.
So, for clear reasons, Asshole really, really had trouble gaming with our furry gamer. He represented everything that this guy was trying to convince himself he wasn't; the pale, nerdy, awkward guy who loved gaming. Honestly, the only difference between them was that one of 'em was an asshole and one was a furry, and let me tell you, I much preferred the furry.
So, our furry player quietly mentions he's going to be running a game. Asshole, always looking for a reason to try and drive this guy away from gaming with him, starts making mocking comments, and finally declares that he'd already planned to run a game session that night. Seeing through this obvious bullshit, somebody tells him to knock it off, and we get the details.
System is going to be a homebrew the guy was working on; heroic fantasy, each player has a few 'freeform abilities', and all rolls are opposed. Backstory is important, so he asks us to work on it, and people prep to meet the next week.