It was a multi-day birthday celebration for Kim Kardashian last week, but she was frowning and busty during her Sin City party this weekend.

The reality star, who officially turned 33 on Oct. 21, got engaged to baby daddy Kanye West in Northern California on her actual DOB. Kimmy and her crew then moved on, celebrating on Friday, Oct. 25 in Las Vegas.

She was surrounded by friends and family and she wasn't modest, showing off her boobies in a lacy, corset-top and pencil-shaped skirt. The reality star got her pre-North figure back pretty quickly, and she was flaunting it, despite having a scowl on her lovely face in most of the photos.

Can we ask a question? Kim, why so serious? It was your birthday week and you should have had a perma-smile affixed to your face, 24/7.

The party took place at TAO at The Venetian, with mom Kris Jenner, sisters Kourtney and Khloe and more in attendance to help Kardashian celebrate the double three.

The top and skirt played up her figure and sun-kissed skin. Look at those knockers!

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The newly-engaged and handsome couple. Congrats again, you guys! What do ya think Yeezy is looking at?

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Either Kim sprouted a second head that looks like her mother Kris Jenner -- instant Halloween costume!! -- or this was an accidental photo bomb. AWESOME!

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It's Kimmy and her sisters, sexily coordinated in black and white.

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Newly-separated Kris Jenner was living it up in leather, dominatrix style! She's a hot mama.

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