On Sunday, a few hours after he was found dead in his California swimming pool at age 47, Rodney King—a central figure in the 1992 Los Angeles riots—began trending on Twitter.

News of King's death was quickly followed by a related, if disturbing, Twitter trend: "Who is Rodney King?"

"Who is Rodney King?" Briauna Mariee, identified on Twitter as "First Queen Standing," tweeted upon seeing King's name trending.

"Is it bad that idk who Rodney King is," Twitter user Jiggy wrote, "cause I don't."

"Who is Rodney king again? I forgot," Bougie Bre asked, adding: "#serioustweet."

"Same thing I wanna know," user Carolina Girl tweeted.

"[I don't know] who Rodney King is/was," @IAinTheDadMaury admitted. "Don't feel bad cause idk who he be either," @DatNikkaCuatro responded assuringly.

"I'm not gone lie y'all," @isingiprayilove wrote. "I don't who [...] Rodney King is."

"Wikipedia it," Bennie Cooper suggested in response.

"Don't know who Rodney King is but we share the same last name," Raymond King, a self-described "semipro gamer," wrote on Twitter. "R.I.P."

King's death was certainly not the first to baffle Twitter users. Television icon Dick Clark, author Ray Bradbury, Bee Gees singer Robin Gibb, disco queen Donna Summer, CBS News interviewer Mike Wallace, "Where The Wild Things Are" author Maurice Sendak, singer Levon Helm, Beastie Boy rapper Adam Yauch and hairdresser Vidal Sassoon—all of whom died this year—ended up cycling through the microblogging service in a similar manner:

1. Death is reported

2. News of death spreads

3. Name begins trending on Twitter

4. Name preceded by "Who is" begins trending on Twitter

5. Backlash against ignorant users responsible for "Who is" trend ensues

"I get the feeling I'm going to be slaughtered for saying this," Rhys Kelly tweeted after Gibb's death. "But who is/was Robin Gibb?"

"Who/what on earth is the Bee Gees?" admitted cocoon-dweller Peter Botha asked his followers.

"Who's Robin Gibb and why is she trending?" Ant Wright wrote.

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"We all have a tendency to see culture as a monolith," Scott Lamb, managing editor of Buzzfeed—a site that's become a virtual clearinghouse for Twitter naivety—told Yahoo News recently. "And one thing Twitter does is expose how untrue that notion is."

On April 18, Buzzfeed noted:

Shockingly enough, there is an absolutely gigantic amount of people on Twitter who don't know who someone or something is. Today it's Dick Clark.

"Yes, there are those who don't know about Clark," Jen Chung wrote on LAist.com. "But to be fair, some aren't American and Clark was an American pop culture figure. And the young aren't as familiar with him, because he's only really been on TV lately as the New Year's Rockin' Eve host—and in limited segments."

Of course, it's not just death that exposes Twitter's generational divide—anniversaries of historical news events show it as well.

In April, on the 100th anniversary of the Titanic disaster, the social news-sharing site Reddit pointed to a series of tweets from people who did not know that the sinking of the Titanic was real—and not just a 1997 Hollywood blockbuster starring Leonardo DiCaprio and Kate Winslet.

"Wait!" user Sue D. wrote. "Titanic really happened? I thought it was just a movie."

"Guys, the Titanic was real!" @BabyDoe22 wrote. "#mindblown."

"I think the reason why bigger events exposes the divide is because people just want to participate in the conversation," Chung told Yahoo News. "They want to have a say, even though they might not have anything to say."

"People not knowing about the Titanic probably says more about gaps in the education system than gaps between generations," Lamb said. "But Dick Clark's death does expose that the cultural touch-points we take for granted aren't familiar everywhere."

[Also read: Twitter Backlash for People Who Did Not Know 'Titanic' Was Real]

But you don't always have to die or sink a ship to blow young Twitter users' minds: Sometimes, you just have to be a former Beatle who shows up at the Grammys.

"Who the f--- is Paul McCartney and why is he on this?" Kristen Dewe wrote on Feb. 13 during the Grammys broadcast.

Sadly, she was not alone.

McCartney, who turned 70 on Monday, is among a set of celebrities who have been a constant presence for men and women of a certain age--just imagine what's going to happen on Twitter when Macca dies.

"People just coming of age now have a different group to work with," Lamb said. "There's something unsettling about realizing that your references are dated."