Little did Mariah Carey know that when she uttered "I don't know her" about Jennifer Lopez in the early 2000s, those four little words would become Carey's de facto catchphrase for the rest of her career. And on Sunday's Watch What Happens Live, Andy Cohen did some boots on the ground reporting to see what other famous pop divas Carey does or doesn't know.

While Carey readily admitting to knowing Lady Gaga, Britney Spears and Taylor Swift, she didn't hesitate to play dumb when it comes to the mere existence of Ariana Grande.

"When I looked at her early in the career, I kind of thought, 'Wow, this is an homage to Mariah a little bit," Cohen said. "Did you feel that?"

"Child, I don't know when early in the career was," Carey deadpanned.

Carey also expertly shaded Miley Cyrus, saying she was unsure whether or not she once met Cyrus "in a bathroom." But when Cohen pointed out the pair both performed on Divas Live, Carey delivered this epic response: "I performed on that show a lot of times. Aretha Franklin, Diana Ross - how am I supposed to remember everybody else?"

Later in the episode, Cohen brought up Demi Lovato, who notoriously slammed Carey for her "nasty" treatment of J.Lo, and asked what the pop icon would say to the "Confident" singer.

"I don't know her either, and so I wouldn't say anything to her," explained Carey. "She should come up, introduce herself to me, say, 'Here's my opinion. What do you think about it?' That's how you handle s---, OK?"