Nicki Minaj's butt has been a much-debated subject of speculation and awe.

And like the riddle of the Sphinx or Big Foot's footprint, the 30-year-old rapper is cheekily determined to keep the elusive mystery of her ample assets alive -- at least for now.

The "American Idol" judge took to Instagram Thursday night to share an almost-naked photo of her famous derrière with her legions of followers. Captioning the pic, "#ThongThursdays," the photo shows off her voluptuous rear-end, clad in bright pink thong (and nothing else).

The photo is cleverly cropped, so as not to show Nicki's full behind.

This isn't Minaj's first racy Instagram snap. Last month, she re-tweeted a racy topless photo to her 16.6 million followers, where Minaj is seen barely covering her nipples with her hands.

Will #ThongThursdays be a new thing? Will the self-proclaimed "Black Barbie" ever reveal the secret behind her famous butt? Stay tuned to Nicki Minaj's Instagram account to find out!

More NSFW celeb selfies:

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  • Heidi Klum

  • Sofia Vergara

  • Rihanna

  • Sofia Vergara

  • Rihanna

  • Kim Kardashian

  • Miranda Kerr

  • Heidi Klum

  • Aubrey O'Day

  • Heidi Klum

  • Lindsay Lohan

  • Amanda Bynes

  • Stephanie Rice

  • Pauly D

  • Lisa Rinna

  • Kim Kardashian

  • Demi Moore

  • Rihanna

  • Adrienne Curry

  • Jenelle Evans

  • Sofia Vergara

  • Jordin Sparks

  • Sofia Vergara

  • Miley Cyrus

  • Kim Kardashian

  • Kim Kardashian

  • Rihanna

  • Rihanna

  • Jessica Simpson

  • Nicki Minaj

  • Sofia Vergara

  • Snooki

  • Snooki

  • Amanda Bynes

  • Amber Rose

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