Interesting definition and insight. I like that. Personally, I have to admit that I didn't really give that remark much thought. I just understood it as something playful between B and M, their own language, something that alludes to the comic world of their childhood where they shared those things.
I also thought that it could be a quote from a film or a comic that I don't get. Doesn't seem to be the case.
About the scene and the episode in general; The very first time I saw I wasn't so clearly a B/J shipper like I am now. And I have to say that I still find that scene just very, very hot. There's really a lot of chemistry here, all those suppressed feelings over the years, it's a great scene and it really works for me to understand to Brian/ Michael dynamics. That does NOT mean that I had wanted to see them act on it, it's just so close to that invisible borderline, it's just everything wrapped up in this scene.
I think it's typically Brian to deal with that problem the way he did here - although I still wonder what he would have done if Michael had accepted his "offer". And it's a great step for Michael to get over Brian. He realizes that Ben is giving him the opportunity to stay friends with Brian, to even love him a bit more than he should, maybe, and that this is the real thing, something he doesn't just dream of. I really like that scene where Ben says that we sometimes still love people from our past and that is doesn't matter. Sorry, that's not exactly the question here, but for me, it's related to Michael's reaction.