At the star’s 5th annual Diamond Ball on Thursday night, the “I Like It” rapper, 26, hilariously outbid herself during the charity auction portion of the evening while trying to buy an exclusive signed copy of Rihanna‘s upcoming coffee table book.

At first, Cardi bid $106K on the designer table top book, even though the auctioneer had asked for $110K. After another bidder rang in at $107K, the singer upped her bid to $108K before bidding a final $111K — $1,000 more than the auctioneer had asked for.

“Do you know how this works?” the auctioneer joked, but Cardi — who attended the event with husband Offset — appeared unbothered and celebrated with her hands in the air as she won the coffee table book.

For the glamorous night out, the rapper and Hustlers star stunned in a tiered, light pink gown, while Rihanna wore a black Givenchy Haute Couture mermaid dress, red lipstick and pearl earrings.

At one point during the festivities, the pair — who have been friends for the past few years — posed together for a smiley photo.

Cardi B and Rihanna

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Speaking to PEOPLE at Thursday’s Diamond Ball, Rihanna, 31, said that she was “really happy right now.”

“The thing that’s making me the happiest tonight is seeing the amount of support, the magnitude of support is really special,” the Fenty Beauty mogul shared.

“I mean I could be out here and throw a ball by myself and I’d feel good, but the thing that’s making me feel this high of cloud nine is seeing people who believe in my cause and think it’s something worth donating to, something worth investing in,” she continued.

Rihanna

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Rihanna throws the annual gala in support of the Clara Lionel Foundation, which she founded in honor of her grandparents, Clara and Lionel Braithwaite. The organization supports and funds global education, health and emergency response programs and also engages in advocacy to improve the quality of life of children around the world.

This year’s event was hosted by Late Night star Seth Meyers, while Pharrell Williams and DJ Khaled performed.

It’s been a busy week for Rihanna, who also hosted her empowering Savage x Fenty New York Fashion Week show on Tuesday evening at Brooklyn’s Barclays Center.

The show was a star-studded affair that featured models of all shapes and sizes, including Cara Delevingne, who strutted and danced down the runway, and Halsey, who sang her new single “Graveyard.”