It's meant for everyone, from the cool people who got it right away at the A table where Paul and Harj sit (e.g. https://qht.co/item?id=5371321 ), right on down to the D table where people like me and you sit. You can't have popular without unpopular.
When we were in junior high school, my friend Rich and I made a map of the school lunch tables according to popularity. This was easy to do, because kids only ate lunch with others of about the same popularity. We graded them from A to E. A tables were full of football players and cheerleaders and so on. E tables contained the kids with mild cases of Down's Syndrome, what in the language of the time we called "retards."
We sat at a D table, as low as you could get without looking physically different. We were not being especially candid to grade ourselves as D. It would have taken a deliberate lie to say otherwise. Everyone in the school knew exactly how popular everyone else was, including us.
... and the people at the E table are the hellbanned ones like losethos / SparrowOS, who incidentally might just get up and leave if someone at the A table told them nobody was allowed to talk to them.
Increasing your connection with someone else through an inside joke cuts off anyone who both hears it and isn't in on the joke. That's why the last time georgeorwell encountered inside jokes was in high school: someone else made the joke, he didn't get it, but everyone else did.
Of course georgeorwell has almost assuredly heard inside jokes since. The difference was that he got it and it didn't occur to him that other people wouldn't.
