TiVo just showed me an episode of Family Ties that contained this gem of dialogue:

Elyse: Let’s sit down and have a rap session.
Mallory: What do you want to wrap?
Audience: Laughs
Elyse: No, not wrap with a W, this is rap with an R. It’s a term we used in the 60’s, it means talk. But “talk session” didn’t sound right, so we used to say…
Mallory and Jennifer: Stare blankly
Audience: Laughs

Funny at the time, I guess, but it’s the wrong joke for 2004, where Mallory should be wondering why her mother wants to sing hip-hop music. Ironically, according to the dictionary, that definition is directly descended from Elyse’s 1960s hippie conversations. The word had been used for the music genre for over a decade by the time this episode aired in 1987, but I guess it hadn’t yet hit the popular culture scene.

Personally, I’m not one to know anything about what was popular when. I didn’t start listing to ’80s music until at least 1998. The first rap song I remember being aware of is U Can’t Touch This, circa 1990 or so (a friend of my parents was fascinated with M.C. Hammer as a cultural phenomenon, and bought me a cassette). I certainly would have found the Family Ties gag appropriate when first aired. But it’s definitely a joke that went stale in only a few years.