LAS VEGAS (USA Today) -- Perhaps Robin Thicke has been hanging out with Miley Cyrus too much lately.
Thicke showed some skin during his performance of Blurred Lines near the beginning of Friday's iHeartRadio Music Festival - perhaps more than he intended. As Thicke performed, a button on his shirt either came unbuttoned or popped off entirely, revealing the singer's belly. What's worse, the zipper of his pants came partway down, too.
Thicke laughed off the incident with presenter Ryan Seacrest afterward, but his wardrobe malfunction was an awkward start to a night that was full of more musical surprises.
Miguel came out during J. Cole's set to perform Power Trip with the rapper. Later, Cole brought out TLC to sing his current single, Crooked Smile, with him. Rapper Juicy J joined Katy Perry on Dark Horse, a song that will appear on Perry's Prism album, out Oct. 22.
Former American Idol runner-up Adam Lambert fronted Queen for a 35-minute set that closed the night. fun., which had played earlier in the night, sat in on Somebody to Love and Fat Bottomed Girls.
Perhaps the night's biggest surprise came just before Perry's set, when Norwegian comedy duo Ylvis gave a live performance of The Fox, a viral video that has received more than 42 million YouTube views since being posted earlier this month.
Elton John, Keith Urban, Muse and Chris Brown also performed, and DJs Tiesto and Benny Benassi spun between sets by some of the main-stage acts.
Backstage, Urban said he planned to stay for Muse's set, which directly followed his. He expressed an interest in staying for Queen, which closed the show, but expected that he'd be flying to Los Angeles to watch over his two daughters while wife Nicole Kidman travels to China for an awards ceremony.
"I'm on daddy duty," Urban said. "I'll get home after they've gone to sleep, and I'll be there for breakfast in the morning."
The iHeartRadio Music Festival continues Saturday night at Las Vegas' MGM Grand Garden Arena with sets by Bruno Mars, Justin Timberlake, Paul McCartney and others.