Barack Obama and Kendall Jenner

Though Jenner was overjoyed to meet Obama at the White House Correspondent’s Dinner in 2015 (judging from how much she gushed on her Snapchat immediately after), the former POTUS felt differently. Later in the evening, Obama told the crowd about his experience meeting the “Keeping Up with the Kardashians” star.

“Kendall Jenner is also here. And we had a chance to meet backstage,” Obama said. “She seems like a very nice young woman. I’m not exactly sure what she does. But I am told that my Twitter mentions are about to go through the roof.”

Mariah Carey and Jennifer Lopez

It was the interview that started it all. In the early 2000s, Carey was doing an interview with foreign TV station, which asked for her opinion about various female pop stars. The singer described Beyonce as “nice” and “a good writer.”

However, when it came time to offer her take on Lopez, Carey simply responded, “I don’t know her.” Despite J-Lo claiming on “The Wendy Williams Show” that Carey has met her “many times,” the “Fantasy” singer insisted on “Watch What Happens Live” in 2016 that she still doesn’t know her.

Rob Kardashian and Mehgan James

For a hot second in June 2017, Kardashian battled rumors that he was secretly dating “Bad Girls Club” star Mehgan James. When he caught wind of the talk, Kardashian shut the rumors down with an epic “I don’t know her”-esque tweet.

“Wait reading online about some chick I’m dating Megan something,” he wrote. “Not true never even met her or heard of her before.”

Justin Bieber and Shawn Mendes

Though the singers both hail from Canada and are buddies now, there was a time when Bieber didn’t know who Mendes was. In a 2015 radio interview, Bieber was asked if he had any advice for up-and-coming singers, like Mendes, and impending fame.

In response, Bieber turned his head to his publicist and softly asked, “Who’s Shawn Mendes?” When the interviewer described who Mendes is, Bieber responded, “I don’t know him. But I will check him out, for sure.”

Mariah Carey and Kim Kardashian

In an interview with Howard Stern in 2014, Carey’s ex husband, Nick Cannon, claimed she had no idea who the “Keeping Up with the Kardashians” star was. The two were talking about rumors that Carey was devastated over Cannon previously dating Kardashian. Cannon argued that wasn’t the case, considering the singer had no clue who the E! personality was.

“My wife, she don’t even know who Kim Kardashian is,” Cannon said. “She doesn’t pay attention to that.”

After the interview came out, sleuths pointed out that Carey and Kardashian appeared on an episode of “The Tonight Show with Jimmy Fallon” together, prompting “I don’t know her” fanatics to call shade.

Fifth Harmony’s Dinah-Jane Hansen and Girls Aloud’s Sarah Harding

On a recent episode of “Celebrity Big Brother,” Girls Aloud member Sarah Harding shaded and slut-shamed Fifth Harmony by calling them “slutty” and claiming that they “wear next to nothing.” When confronted with Hardings’s comments, Fifth Harmony’s Dinah-Jane Hansen had the perfect response.

“I don’t know who she is,” Hansen said. “If she wants some lessons or something–people always want to learn how to booty pop like Fifth Harmony. But shout-out to her. Keep doing you, girl. I really don’t know who she is.”

Mariah Carey and Ariana Grande

Mariah Carey’s at it again: On an episode of “Watch What Happens Live” in 2016, host Andy Cohen asked her if she knew a series of pop stars.

When the conversation landed on  ArianaGrande and Cohen asked Carey if she knew her, the singer responded with a simple, “No.” She elaborated, “Honestly, I’m not familiar. I listen to hip-hop more than I listen to pop music.”

Mariah Carey and Demi Lovato

On the same episode of “WWHL,” Cohen pressed Carey to see if he knew Lovato. The host brought up recent comments from Lovato, in which she said Carey’s treatment of Lopez was “nasty.” In defense, Carey responded, “I don’t know her either.”

Iggy Azalea and Halsey

When Iggy Azalea learned that Halsey dissed her in an interview by calling her a “moron,” the “Fancy” rapper had this to say.

“To me, because I’m a famous person and I know a lot of the time people have opinions and they’re not always accurate, I really try very hard not to give my personal opinions about people that I don’t know,” Azalea said. “And I don’t know her, I’ve never met her.”

Jerry Seinfeld and Kesha

Jerry Seinfeld was an in an interview on a red carpet in June when “Seinfeld” superfan Kesha asked him for a hug. As the singer approached him, Seinfeld threw his arms up and told her, “No, thanks,” which prompted Kesha to walk away embarrassed.

“I don’t know who that was,” Seinfeld said afterward.

In an interview with “Extra” not too long after, Seinfeld defended his reaction. “I’m 63, I don’t know every pop star,” he said. “I don’t know everyone.”

Christopher Nolan and Harry Styles

Before the One Direction member acted in the director’s film, “Dunkirk,” Nolan knew next to nothing about who Styles was. In an interview before the release of his movie, Nolan revealed that if it wasn’t for his teenage daughter, the name “Harry Styles” would likely to have never rang a bell.

“I don’t think I was that aware really of how famous Harry was” before casting the pop star in the upcoming World War II epic, Nolan said. “I mean, my daughter had talked about him. My kids talked about him, but I wasn’t really that aware of it.

George W. Bush and Jay Z

Though the former POTUS knew who Beyonce was, he drew a blank at the singer’s husband, Jay Z. When asked about “Formation” singer in an interview with Jimmy Kimmel, Bush offered the only detail he knew about her. “She’s from Texas,” he said.

However, when it came time for Kimmel to ask if he knew who Jay Z was, Bush came up short. “No,” he responded matter-of-factly.