I mention this because of two items of recent entertainment that both involved inside jokes. The first was the new Coen Brothers movie, A Serious Man. In case you haven't seen a review, it's something of a riff on the story of Job, set in a Jewish neighborhood in suburban Minneapolis in 1967. Larry Gopnick has to deal with the upcoming decision as to whether or not he'll get tenure (which is complicated by a student attempting to bribe him), repeated calls from the Columbia Record Club demanding money, and a lot of general family tsuris (an unfaithful wife, his son's impending bar mitzvah, his unemployed / unemployable brother). He consults a series of rabbis in an effort to make sense of what's going on - and gets an answer that amounts to "we can't know."
I found the movie extremely entertaining in a dark comic way. But I also found myself wondering if anybody who wasn't Jewish would follow it at all. It even starts with a mysterious shtetl incident (in Yiddish, with English subtitles). I've seen reviews by non-Jewish reviewers which seemed somewhat positive, but I'm sure those reviewers weren't sitting there nodding their heads the way I was. I can wholeheartedly recommend the movie to others who grew up in Jewish suburbia in the 1960's, but I'm not sure I can go further.
The other item of insider jokes was The Musical of Musicals (The Musical), which I saw at Metro Stage in Alexandria. Take the basic melodrama plot of the ingenue who can't pay her rent, the landlord who demands the rent, the older woman who offers helpful advice, and the boyfriend who rescues the situation. Now, make it into a musical. No, make it into five musicals in five different styles. Corn was in the style of Rodgers & Hammerstein. Then came A Little Complex (Stephen Sondheim), Dear Abby (Jerry Herman), Aspects of Junita (Andrew Lloyd Webber, and Speakeasy (Kander & Ebb). The pastiche was right on the mark and the whole thing was very funny. That is, it's very funny if you're enough of a theatre geek to catch the jokes. Some of them are broad enough that you probably don't have to know much. But I'm not sure if the average audience member ccould catch things like the boyfriend coming to rescue the ingenue from the landlord in the Sondheim section because "he was making specific overtures."
By the way, one of the things I really liked was that it was obvious the cast was having fun. Bobby Smith (as the landlord) was particularly notable, but all five performers (the fifth was the pianist / narrator) were excellent. Again, this is something I can wholeheartedly recommend, but only to a specific prospective audience.