So you refuse to hang out with any of the millions of Reddit users because some of them laughed at you for not knowing what tl;dr meant?
I've been merrily using Reddit since 2007, but I wouldn't go to a Reddit meetup. Why? Because the "Reddit" culture is one I don't particularly find interesting. It centres around bad in jokes, immaturity and sexism.
There are definitely interesting parts of Reddit, but for me (and I'd imagine others) the culture which some users (unfortunately the loudest) identify with as being "Reddit" is quite immature and tedious.
Perhaps at one point Reddit was a shared interest which could lead to interesting conversations, but for quite some time the size of the community (and its spread in topics) means that the only shared interest of redditors (judging from the front page right now) is memes and funny pictures.
TL;DR The millions of Reddit users you'd actually want to hang out with probably wouldn't turn up to a Reddit meetup.
Presumably it varies a lot from region to region. Like subreddits, but harder to subscribe to.
Chances are many people I hang out with use 4chan, but I avoid people that I can tell use 4chan. The reason is that these classifiers, unlike so many others, can be used as indicators of behaviour or attitude.