Slave for Britney Spears! Nicole Richie joined the pop singer on stage during her Tuesday, Feb. 18 concert at Las Vegas' Planet Hollywood. The 32-year-old fashion designer, and Spears superfan, was pulled up on stage during a raunchy performance of the singer's "Freak Show."

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Richie shared photos on Instagram from the wild night that included her crawling like a dog on stage while Spears walked her on a leash. In one snapshot, Richie gives Spears, 32, a big hug while surrounded by her scantily-clad male backup dancers. She captioned the embrace: "#GOODBYE." In a second picture, Richie is seen laughing while holding up a large T-shirt with Spears' face on it.

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"Can we all give a round of applause to @NicoleRichie for playing along in the show tonight?" Spears tweeted early in the morning on Feb. 19. "U looked hot crawling on all fours."

The "I'm a Slave 4 U" singer also tweeted Richie directly: "@NicoleRichie Thanks for dancing tonight! xoxox." Richie replied back: "Am I alive?"

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This isn't the first time Spears had made a celebrity join her on stage and crawl on all fours. Mario Lopez and Lance Bass had the honor last year, as well as Spears' boyfriend David Lucado.

This article originally appeared on Nicole Richie Hugs Britney Spears, Crawls on All Fours During Concert: Pictures