Katy Perry is the latest surprise guest to join the Rolling Stones on stage during their "50 and Counting" tour.

On Sunday night (May 12), the "Teenage Dream" singer joined Mick Jagger on stage at the MGM Grand Garden Arena in Las Vegas to perform "Beast of Burden."

"Yes, I just did gyrated on Mick Jagger. WHAT?!" she tweeted following the show.

"Thanks for letting me be the 5th wheel last night," she added later, along with a photo of herself posing with the rock legends.

Gwen Stefani, Tom Waits, John Fogarty, Bonnie Raitt and Keith Urban have also joined the band on stage since the 17-date tour began in Los Angeles earlier this month.

Watch footage of Katy Perry perorming with the Stones here.

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Katy Perry is halfway through the recording process for her third album, Billboard reports.

During a session at the ASCAP's I Create Music Expo for songwriters and composers on Thursday (April 18), the pop star revealed that she is collaborating with many of the producers and songwriters that worked on her Teenage Dream album, including Bonnie McKee, Max Martin, Dr. Luke and Greg Wells.

"When I put myself on a timeline, when I tell the record company when I want to release the album, that's when the race starts," she said. "That's when I put pressure on myself."

She added: "Max and Luke push me the most. As a team we have certain strengths. With Max, it's melody choices, Luke is production and I'm topline and melody."

Although she did not go into many specifics about her forthcoming record during the career-spanning talk, she revealed that she has recorded a song with Greg Kurstin and Bonnie McKee called "Double Rainbow" that might make the final cut.

"She came in from a yoga class and said, 'I want to write a song called 'Double Rainbow.' So we have a song called 'Double Rainbow,'" Perry said.

We can also expect some throwback production flourishes that are apparently coming back into fashion. "You know the '90s are back when you're voluntarily putting record scratches in your songs a la Portishead's Dummy," she tweeted.

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Justin Bieber fans are apparently cutting themselves and posting photos online to pressure the pop star to quit smoking pot.

Complex reports that message board 4chan started spreading the hashtags #cutforbieber and #cuttingforbieber as a joke. However, the 19-year-old pop star's young fans have taken the meme seriously and the hashtag began trending on Twitter.

The disturbing prank is a response to photos posted online by gossip site TMZ that show Bieber holding what looks like a joint at a Newport Beach hotel room party.

On Tuesday (January 8), a rep for British charity YoungMinds called the joke "irresponsible, reprehensible and extremely dangerous."

"Self harming is not a fashion, fad or statement," Lucie Russell told The Independent. "It's a signal that young people are experiencing extreme distress and need help. Cutting is a self-destructive act that is a way of coping with overwhelming emotions."

She added: “To suggest young people cut themselves as some kind of protest is a very perverted and dangerous idea, and these people need to take responsibility and stop this activity immediately.”

After the photos appeared online, Bieber tweeted a pair of repentant remarks but did not directly acknowledge the brewing scandal.

"Everyday growing and learning. trying to be better. u get knocked down, u get up," he wrote. "I see all of u. i hear all of u. i never want to let any of you down. i love u. and..thank u."

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Katy Perry has released an extended director's cut for her music video "The One That Got Away."

This seven-minute version of the video, which features extra footage at the beginning and end, was originally shown in cinemas a year ago.

The video stars Perry as an elderly woman in a loveless marriage that has a flashback to a tumultuous relationship earlier in her life. It was directed by Floria Sigismondi, co-stars actor Diego Luna and features narration from Fleetwood Mac star Stevie Nicks.

Watch the director's cut of "The One That Got Away" here.

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Katy Perry has reportedly started working on her third studio album.

According to the blog josepvinaixa.com, the pop star has reunited with producer Greg Wells ("Ur So Gay," "Waking Up in Vegas") and songwriter Bonnie McKee ("Teenage Dream," "California Gurls") to work on the collection, which is due for release in summer 2013.

It has not been confirmed whether she will re-team with hitmaking producers Dr. Luke and Max Martin as the duo signed an exclusive deal to produce for Sony Music and Perry is signed to EMI-owned label Capitol Records.

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The singer for Toronto electronic duo Crystal Castles has lambasted pop star Katy Perry for promoting over-sexualized images of women to young girls.

In an interview with NME, Alice Glass took umbrage with the "Teenage Dream" star's double entendre laden 'California Dreams' tour, which featured a whipped cream cannon, among other cheeky props.

"We need an army because the mainstream hates women... A lot of kids are more sexualized now than they were years ago and I'm not sure it's a coincidence," she said. "Like f***ing Katy Perry spraying people with her f***ing d***, her f***ing c** gun coming on f***ing children. And little girls, like six-year-old girls wearing a shirt with 'I wanna see your [pea] cock' on it... Don't prey on vulnerable people like that. Don't encourage little girls to get dressed up, to have cupcakes on their tits to get people to lick them off, 'cause that's what you're insinuating."

Crystal Castles will release their third studio album (III) on November 12.

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We are live from the red carpet and behind the scenes at the 2012 MMVAs in downtown Toronto. Stick with us and we'll give you an insider's view to spot all the stars, including Katy Perry, Kelly Clarkson and our own Justin Bieber!

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