On Thursday, the Walt Disney Studios Instagram account gave Miranda, 38, control of the page for day. Unsurprisingly, the results were pure magic. This is most clear in Miranda's pics and videos with 35-year-old Blunt, his Mary Poppins Returns co-star.
In perhaps the best video, the duo sings "A Whole New World" from Disney's Aladdin, much to the delight of fans.
"I can show you the world," Blunt, wearing a striking pink shirt, sings in the role of Aladdin.
"Shining, shimmering, splendid," they sing together, before arguing over which one of them in the princess with the next line. Miranda, wearing a blue sweater, eventually accepts that he's the princess, "Oh thank you," he responds to the distinction.
"When did you last," Blunt sings before Miranda joins in with, "Let your heart decide?"
"I can open your eyes," Blunt sings amid giggles, while holding open Miranda's eye.
"Aladdin rehearsal #Linstagram #MaryPoppinsReturns #IAmThePrincess #WeAreNotInAladdinWeAreInMaryPoppinsReturns," Miranda captioned the hilarious post.
He also tried to use Boomerang, revealed why he used a Prince Harry mask, and shared a selfie with Dick Van Dyke. He even posted a video recreating a classic America's Next Top Model moment with Tyra Banks!
ET caught up with Mary Poppins herself back in March, where Blunt revealed that she was scared of her character's flying scenes.
"I'm not amazing with heights and it was one of those things where they kind of [get] you up there and there's the moment before they bring you down for the shot, and it seems like that moment extends for a forever time frame," she said. "You're so high that if you look out you're higher than the trees and you look down. ... But it was an incredible moment, you know. Very disarming."
Of the Hamilton creator, Blunt kept it short and incredibly sweet. "Awesome. So talented. So cool," she gushed of Miranda.
Watch the video below for more of ET's sit-down with Blunt: