As shown in the clip, the video opens to Perry -- who welcomed daughter Daisy with Orlando Bloom in August -- pushing a stroller while on a walk. However, Deschanel was sitting nearby and as a result found herself getting abducted by two blue aliens, who had been tasked with kidnapping Perry but accidentally took Deschanel due to their similar appearance.
After Deschanel is beamed up, the "New Girl" actress made a deal with the aliens and agreed to pretend to be Perry in order to save Earth. Deschanel then underwent a Perry-style makeover, complete with some of the singer's infamous looks, including her "California Girls" blue wig and whipped cream shooting bikini.
The video then concluded with Deschanel, who had saved Earth, performing as Perry for the alien planet.
Watch the video, below!
Later on Monday, Perry and Deschanel went live on Perry's Instagram to chat about the video.
Since Perry was on maternity leave when the music video was to be shot, she recommended Deschanel to star in it.
"I had just had Daisy," she recalled to Deschanel, 40. "I called you up and I had this idea that Zooey would step in while I was taking a little bit of a leave."
"I was like what a great chance because for so long we have had this funny relationship -- friendship -- but obviously people think we look alike," she added, to which Deschanel agreed, saying she takes being mistaken for Perry as a "compliment."
Also, during the chat, Perry revealed that when she first moved out to Los Angeles she told people she was Deschanel in order to get into clubs.
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"When I moved to LA maybe 18 years ago...I was pretty much a nobody and you were just getting huge at that time like Zooey Deschanel ran the world at that particular moment," Perry recalled. "In that moment, I was so complimented to look like you."
She continued, "I have to admit something to you on a Live that when I first got to LA I went to the club a lot and wanted to get into the club and I had no money and I had no clout. I had nothing and sometimes I would pose as you to get into the club."
However, this wasn't news to Deschanel, who said she was such a "goody-two-shoes" at the time that when people said they saw her at the club, she knew something was up.
"Everyone kept telling me about this Katy...I was like, 'Who is this Katy?'" Deschanel shared. "And then when I met you I was so relieved because you are so pretty. I was like 'Oh, thank God. She's so pretty!"