Jimmy Fallon and Paul McCartney switched accents in a Freaky Friday parody on Fallon's late night show on Oct. 7. 

McCartney was Fallon's musical guest on Monday night, and Fallon took the opportunity to steal one of Sir McCartney's most treasured assets, his rich Liverpool accent.

In the clip, Fallon and McCartney are seen backstage, walking down the hallways of the studio, talking on the phone. Fallon is discussing his Halloween costume with a friend, deciding that the get up of a "slutty astronaut" would be perfect. McCartney is heard talking about The Beatles' 1968 hit Hey Jude: "The J was just a typo, the song was actually supposed to be called Hey Dude."

The two bump into each other mid-conversation and the Freaky Friday-esque swap happens. As Fallon quickly apologizes to McCartney, he does so with true Britsh sophistication while McCartney attempts a southern drawl, saying, "No problem, Jimmy."

While McCartney thinks its awful that he has an American accent now, Fallon is psyched about having the voice of a Beatle, and he rattles off some English platitudes -- "I'm from Liverpool, let's have a spot of tea" -- just to test his new-found English accent.

McCartney pleads to Fallon, asking him to return his accent. "C'mon mate, can't we just Let it Be," Fallon quips in a sing-song voice. He carries on to make a bunch of American pop culture references -- "SpongeBob SquarePants," "Here Comes Honey Boo Boo," and "Let me see what you are twerking with" -- in an English accent.

Eventually McCartney has to bump his head against Fallon's to undo the spell.

Watch the clip: