"In my birthday suit," the pop star wrote. "The girl can't help it! Thanks for all your good wishes!"
She added the hashtags #grateful and #livingforlove, so it sounds like she's having a pretty good day. Lourdes, on the other hand, is probably cringing in embarrassment as she finishes lighting the candles on Mama's birthday cake.
Not many 56-year-olds would ring in their special day by freeing the nipple, but Madonna's never been one to shy away from going the NSFW route. Party on, Madge.
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