We all have gaps in our knowledge that we are unaware of, but sometimes those can be astonishing, as when a woman in her 20s told me that she had just learned Jackie O. was the widow of JFK. Same person. Who knew?
Another example, anecdote found online:
In 2004, I went to Cleveland to canvass for John Kerry, and when we got to the campaign center, they told
us (me and some college students) "Too bad you weren’t here five minutes ago, Matt Dillon and Paul
Newman were just here." One of the students asked me "I know the salad dressing but what else did Paul
Newman do?" I said "The Hustler, HUD, Butch Cassidy, The Color of Money," and the students all looked
at me blankly, having never heard of any of these movies.