Keith Urban doesn't always follow the rules. Lately, the Australian superstar has even gotten in trouble on 'American Idol' -- so much so that he has to have his outfits pre-approved!

Shockingly, Urban's cool and casual wardrobe -- namely his T-shirts -- are getting the 'Cop Car' singer in hot water with producers.

“I have to check with the Idol people sometimes because sometimes [my T-shirts] aren’t appropriate," Urban explains to Ryan Seacrest (quote via US 99.5). "Every now and then, [they tell me I can't wear one]."

He adds, "Let’s just say, I have to take a picture of my shirt and send it to them.”

Once Urban sends the photo, the producers have to give a thumbs up before he can wear the shirt in front of the cameras.

Aside from judging the biggest reality singing show, Urban is keeping himself busy doing what he loves -- performing. He has dates in his homeland of Australia for much of June, and then returns to the U.S. for some late summer and early fall tour dates. Full dates are listed on his website.