Jimmy Fallon and Ariana Grande star in 'Ew!' sketch for 'Tonight Show'

Comedian Jimmy Fallon and pop star Ariana Grande dressed as tween girls for his popular Tonight Show segment "Ew!"
The clip has been viewed nearly 3 million times since it was posted on YouTube Friday.
At one point in the video, Fallon's Sara character challenges Grande's Alexa to an "Ew!" sing-off.
Sara garbles a bunch of notes before passing off to Alexa.
"I can't top that," Alexa deadpanned.
"You have to try," Sara encouraged her.
After Alexa sings a pitch-perfect "Ew!", Sara tells her, "That was OK, I guess," and shrugs.
The pair then broke into giggles as they debated whether actor Richard Dreyfuss was cool or Ew!, then toasted their friendship with Shamrock Shakes from McDonald's.