Keith Urban talks inspiration behind new 'sexy a-- song' about wife Nicole Kidman

Nicole Kidman may be a lady in the streets but she's a freak in the sheets, according to her husband Keith Urban!

The 50-year-old country singer gave fans a little too much information about his sex life with the Aussie actress in his new single, 'Gemini.'

"She's a maniac in the bed but a brainiac in the head," sang Urban. "She'll wake you to make love in the middle of the night."

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The lyrics come as a shock, especially from a couple who are usually private about their relationship. So, why the surprise kiss-and-tell?

"[It's] just a simple, fun, sexy-a--- song about my wife," Urban told the Daily Telegraph today.

There was a time when the singer would not had been comfortable singing about Kidman, 50, in this way. But now that they're one month shy of their 12th wedding anniversary, there's no harm spicing up their love lives.

And all it took was a little encouragement from songwriter Julia Michaels -- who co-wrote the song with him -- for Urban to include the racy lines.

"She goes, 'It's a fun song, just sing it,'" he recalled to The Australian. "I couldn't argue with that logic, which is 'You feel that way about your wife, it's about your wife, it's super fun it's super sexy. Just f---ing say it.'"

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In another interview with KIIS FM radio duo Kyle Sandilands and Jackie O, Urban admitted that the reason his relationship with Kidman is still going strong is because they really do love each other.

"I think being in love is genuinely the reason for success," admitted Urban.

And Kidman's midnight nudges help too, right?

"If you have a happy wife, you have a happy life," he said.

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