Miley Cyrus Exposes Br**st, Twerks in Lil' Kim Costume at HalloweenParty

Happy Twerking Halloween! After revealing her (predictably) over-the-top Halloween costume on Twitter earlier in the day on Thursday, Oct. 31, Miley Cyrus took her alter ego out for a night on the town. The 20-year-old singer dressed up in Lil' Kim's half-topless purple jumpsuit from the 1999 MTV Video Music Awards. The infamous ensemble completely exposed Cyrus' right breast, which was concealed only by a purple pastie.

Wearing a purple wig and the ultra-sexy costume, the "We Can't Stop" singer attended Adam Lambert's Halloween for Charity party powered by CIROC at Bootsy Bellow's in West Hollywood Thursday night. An insider told Us Weekly that Cyrus arrived around midnight and headed to a booth near the DJ. She stood up on the table was reportedly smoking an electronic cigarette while dancing and twerking. "No one was dancing as provocatively as Miley," the eyewitness told Us. "She was dancing seductively while grinding against her girlfriends and twerking."

Cyrus danced to Missy Elliott's "Work It" and Snoop Dogg's "Drop It Like It's Hot" while "flirtatiously shaking her butt and moving along to the beat," the source said.

No stranger to nudity, the "Wrecking Ball" singer's half-topless ensemble didn't appear to inhibit her partying -- it only enhanced it! "Miley was dancing with her girlfriends, shaking and shimmying and began tapping at her bare breast that was covered with the purple sequined pasty," the eyewitness said. "She had no shame flaunting her body."

What did Lil' Kim think of Cyrus' copying her look for a Halloween costume? She loved it! In an interview with MTV on Thursday, the 39-year-old rapper gave her stamp of approval.

"How awesome was that! Put it this way, she did me very well. I think she looked gorgeous. I love her; she's one of my besties," she said. "She's like my bestie-slash-wifey. You know what's so funny? As soon as she tweeted the picture, she texted me and was like she was like, 'Happy Halloween, babe!' . . . I think she did me well."