Katy Perry has adopted a group of crazy new characters for her latest music video, performing at birthday parties undercover.

The Firework singer reveals she was tired of playing dressed-up sexpots in dramatic promos and decided to have some fun with candid camera footage for the Birthday shoot.

In the video, she plays a Jewish comedian called Yosef Shulem, aged British dancer called Goldie and Kriss the Clown.

She says, "I went undercover as five of the world's worst birthday entertainers because I was sick of making, like, gorgeous music videos where I'm, like, sexual... I just feel that can get boring... so I made the most insane music video ever with hidden cameras.

"These are real birthday parties, where there was a real bouncy castle and I was this character, called Kriss the Clown... She's on parole and she's got some problems; she found the job on Craigslist."

The video features scenes of Perry, as Kriss, causing a traffic accident as she wanders into a road blindfolded at a kids' party.

She adds, "It was kind of actually dangerous; I had three security (men) undercover."