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.