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By Sierra Marquina

Singer and American Idol judge Keith Urban phoned in to On Air with Ryan Seacrest to talk Season 13 and his new single “Cop Car.”

On Tuesday night’s live Idol, we saw the Top 10 girls make the cut … but also, Keith donned one of his signature t-shirts, an item of clothing that surprisingly gets him in trouble at times.

“I have to check with the Idol people sometimes because sometimes they aren’t appropriate,” Keith laughs of his tight tees. “Every now and then [they tell me I can't wear one]. Let’s just say every now and then, I have to take a picture of my shirt and send it to them.”

As far as the talent goes, Keith is proud of this season. “I like the fact we’ve got some really good young ones in here … extremely good singers … but it’s so much more than that [at this stage] … I was saying to Nic [wife Nicole Kidman] the other day when you get to the Top 30, they can all sing. They’re all great singers, so then for me, it’s the ones who make me feel something, that’s what it all comes down to.”

When he’s not helping make other artists’ dreams come true, Keith is also working on his own music. Most recently, the country superstar released “Cop Car” off his album Fuse.

The song is about a young couple who fall in love in the back seat of a police cruiser, and considering Keith is a songwriter himself, where’d the idea come from?

“This is a song that a friend of mine sent to me,” he explains. “It was written by three guys in Nashville and I do a lot of songwriting, but every now and then I come upon a song that just speaks to me and I had never heard that before.”

Catch American Idol on FOX Wednesday and Thursdays at 8/7c.

Download “Cop Car” on iTunes now here.