Justin Bieber and Jimmy Fallon. Picture: Screengrab/YouTube

Jimmy Fallon has a reputation for getting celebrity guest to help him pull off pranks, and Justin Bieber was his latest accomplice in New York City's Central Park.

The pair disguised themselves in ’70s-style suits and ties, and fans had absolutely no idea who they were as they lipsynced and danced to Bieber’s 2015 hit “What Do You Mean?”

No one seemed to recognise the pair, and it was only when the duo whipped off their wigs at the end of the stunt that people in the park realised who they really were, and swarmed them for selfies. 

The comedy bit was filmed in August but only aired on Thursday’s broadcast of “The Tonight Show” with Jimmy Fallon.

Meanwhile, Bieber and his fiancee Hailey Baldwin were also spotted at the NYC Marriage Bureau on Thursday. According to people.com, Bieber got all teary-eyed and allegedly told Baldwin that he could not wait to marry her.

The couple got engaged in July.

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