I actually kind of agree with Rich. In jokes are, by their nature, exclusionary. In fact, I think they’re rude in front of another person who might be experiencing uncertainty about his or her situation with you. When you meet someone new, especially if you’re welcoming that person into your home or a new community, you shouldn’t be using the argot that he doesn’t speak.
Naturally, I’m not saying don’t make in jokes. And what played out upthread was just fine, and everyone was gracious about it. But I’m with Rich and Tim in that I think a lot of people don’t realize how socially awkward in-jokes can be for the folks who aren’t “in”, especially in person. Put yourself in that person’s shoes. For all he knows, you’re having a laugh at his expense. At the very least, you’re making him unsure how to react. Does he laugh politely, or does he risk your scorn by telling you he doesn’t understand?
-Tom, who once had dinner with THE Miss Manners. No joke.