Cultural markers

Razib over at Gene Expression brings up an interesting observation:

Hung with old college friends last night. We kept referring to South Park episodes to illustrate a point or make an analogy so as to clarify an issue. Interesting that this is a common touchstone for my generation.

I'm mid-boom: born 1956, high school class of 1974, college 1978. Of course, I don't see any number of school friends at the same time any more, but I think teevee as a common language fades fairly quickly over time. That is, people I went to grad school with in the last decade might refer to teevee episodes, but high school friends and college friends from thirty years ago would be more likely to refer to song lyrics or movies for cultural references.

There're two or three possible conclusions you can draw from that: Razib's generation is more teevee oriented than mine, his teevee is more memorable than mine, or teevee fades from our cultural language faster than movies or music. I'm inclined towards the latter, but maybe you have your own theory. When you get together with old friends of the same generation, what cultural references do you use for a common touchstone?

I'll add a complication. The group I graduated from high school with were very close in age and clearly of the same generation. In college, our age spread was much larger, but most of us were of the same generation, just different parts of it. By the time I went to grad school in the nineties, the group I socialized with covered two generations with a few outliers from a third generation. When you get together with people from your past, in a group who are not from the same generation, what common cultural markers do you share?