@Madonna/Instagram

Madonna still doesn't have her own regularly-updated Twitter feed, but she's finally joined Instagram, the online photo-sharing service.

And in true Madonna fashion, she made her debut in quite a provocative manner.

To get things started, Madonna posted a picture of herself sipping a martini, along with the caption, "Cheers motherf***ers! I'm on Instagram!"

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She followed that up with a close-up of her sweaty cleavage, along with the caption "Addicted to Sweat!!"

"Addicted to Sweat" happens to be the name of one of the exercise regimens at Madonna's Hard Candy chain of fitness clubs, the most recent of which is opening in Rome. It's also the name of a series of DVDs featuring the workouts, which came out last year.

The other photos Madonna has posted to her Instagram account feature her on stage last year during her record-selling MDNA tour.

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Stay tuned for more.