Ben Casnocha discusses the problem with inside references:
When you make inside references and outsiders read/hear them, outsiders do not understand the content itself and, more importantly, feel excluded. They’re in the outgroup. Sometimes the effect is trivial or inconsequential; other times it’s small but meaningful.
I’ve been in group meetings where a few people who’ve worked together a long time crack an inside joke and all of us who didn’t get it immediately feel like outsiders (relative to whatever bond they have). The people in on the joke feel closer, but this isn’t great for overall team work and team bonding.
Romantic couples tend to do this a lot, actually, and it’s annoying. You’re out with a couple and they turn to each other and wink or quietly chuckle for a moment and while they feel closer, you’re simply reminded of your outsider status relative to their communal bond.
He explains how we can give a nod to insiders without alienating outsiders:
One idea: use “Invisible Winks” in your writing or speaking. A real wink, the closing of one eye, is a non-verbal cue to another insider usually about some mutually known knowledge. But a real wink is often seen by other (outsiders) in a physical context; it’s also impossible to deploy in a written context. That’s why the effective wink I’m talking about (in-person or in writing) needs to be “invisible” and context-agnostic. The key to an invisible wink is that insiders get the wink while outsiders do not notice the wink; additive to insiders, neutral to outsiders.
His bottom line:
The best inside references strengthen bonds with those who get it while not being so obviously inside baseball that outsiders feel excluded.
Coming from an intercultural studies background, this is quite interesting. I believe this has a lot to do with identity. We are quick to communicate in ways that strengthen the bonds of those in our supposed in-group because by being a part of an in-group, we are creating an identity marker for ourselves. We have to be very careful not to look down on those who are not in our in-group. That is when problems can occur.