PHOTOS: Hills stars -- how they've changedRead articleAnd during an appearance on Watch What Happens Live Monday, Dec.

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Chris Brown is back on Twitter, but it's his Instagram account that's getting all the attention now.The 23-year-old singer shared a sexy photo of himself hanging out with Rihanna on Sunday, Dec.

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"What would music today sound like if these kids didn't exist?" Brown wrote as the caption.In the photo, Brown poses with a cigarette hanging out of his mouth as Rihanna, 24, lounges next to him in a bra and underwear, with a camouflage blanket wrapped around her.

PHOTOS: Rihanna through the yearsRead articleBrown isn't the first one to share a provocative photo of the two.

On Nov.I hope you guys had as much fun as I did.

”READ IAN’S PREVIOUS DISPATCHESNov.14Read articleNov.

15Read articleNov.16Read articleNov.

17Read articleNov.