Justin Bieber Went Undercover To Prank 'Friends' Fans And It Didn't Go To Plan

“Dang. Are you serious?" the pop star responded to one couple who didn't realize it was him until much, much later.

Justin Bieber dressed up as a photographer to surprise “Friends” fans on Friday’s episode of “The Ellen DeGeneres Show.”

But it didn’t go entirely to plan.

One couple taking a tour of the hit sitcom’s set at Warner Bros. Studios in Burbank, California, didn’t realize it was the pop star who was taking pictures of them until they were sat in the “Ellen” studio and the segment was being aired.

“Dang,” Bieber told the couple. “Are you serious? You had no idea until right now? You thought it was just some weird guy?”

Check out the clip, and watch until the end, here: