I'm over 20, and I've never heard of the author, group, song, or movie. For another data point, I know plenty of people who had never heard of The Princess Bri

I'm over 20, and I've never heard of the author, group, song, or movie. For another data point, I know plenty of people who had never heard of The Princess Bride, Firefly or Monty Python before me telling them. There is no level of popularity which ensures universal familiarity. You should always assume ignorance is genuine. See also: http://xkcd.com/1053/ http://xkcd.com/1053/