See photos of Rihanna's zombie Halloween costume including a topless selfie of her getting ready to celebrate on Oct. 31. Credit: Courtesy of Rihanna

Topless zombie! Rihanna posted revealing photos of her Halloween celebration with pals on Instagram Thursday, Oct. 31. The 25-year-old singer dressed as a zombie this year and shared a topless "before" picture of herself getting ready.

"#prep," she captioned the sexy selfie. In the snapshot, Rihanna goes topless and shows major cleavage. She strategically covered herself with her newly tattooed hand while grabbing her neck. The "Diamonds" singer appeared to be wearing goth makeup with black lipstick.

She later shared a photo of the nearly fully-dressed finished product, which consisted of an open plaid shirt with a bra top underneath with blood splattered on it. She also exposed the top of Tommy Hilfiger boxers by sagging her pants, and wore big gold hoops and a bandana in her hair. She wrote as the caption: "My chola name was #ShyGirl."

Her friends all dressed similarly and she posted a group photo taken by photographers Gomillion & Leupold with the caption, "ARLETA ZOMBIE CHOLA PACK!!!"

Rihanna also posted several snapshots of herself smoking during the party, and enjoying a Halloween-themed cake. "Just got Heauxm to this EPIC phucking cake from my Bajan chef!!" she wrote. "Thank you Esther!! Ya too sweet!! #BajanHalloween #Barbados."

The "Stay" singer celebrated Halloween one day after performing in Puerto Rico for her Diamonds World. "#PuertoRico I'm truly blown away by you!" she tweeted Wednesday. "Thank you so much for giving me one of the best nights on tour!!"

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