Katy Perry Sings ‘Teenage Dream’ with Keenan Cahill (VIDEO)

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See what celebs show up in Katy Perry's new video.
Internet sensation Keenan Cahill’s teenage dreams are coming true! The famous lip-syncher was finally able to perform alongside his favorite pop star Katy Perry!!!

Keenan met with Katy backstage at the Wells Fargo Center in Philadelphia, PA where she sang with him in full costume with the help of a furry purple friend! The up-and-comer tweeted about the experience, writing: 

“Me and katy perry doing Teenage Dream :) Thanks so much katy for everything.”

He not only got to hang with her backstage but onstage as well.

Check out this video of the two and the colorful mascot performing “I Wanna Dance with Somebody” while in Phili!

Keenan recently sat down with Celebuzz and talked about his adoration for Katy. He said of his celebrity crush: 

“People keep asking why I’m so nervous to meet her. I listened to her before she even tweeted about me and now I follow her even more.”