Happy birthday Crystal Harris AKA. Mrs. Hugh Hefner!

The Playboy bunny turned a whopping 28 years old on Tuesday, April 29 (the same day as Kate Middleton's and Prince William's wedding anniversary) and lucky us, we've been able to witness the blond beauty's transformation from "No. 1 Girlfriend" to sexy wife thanks to her Instagram account.

Like Wayne Gretzky's daughter Paulina Gretzky, Crystal is also a fan of posting lots of sexy bikini photos and, in total Playboy style, enjoys getting decked out in nothing but body paint.

The Arizona-native's birthday comes just a few weeks after Hef's 88th, and the couple, who've been married for a year and a half, will no doubt be celebrating in style.

So, in honour of Crystal's birthday, we take a look at her hottest Instagram photos. Enjoy!

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  • NEXT: Hugh Hefner's Best Instagram Photos

  • Hugh Hefner And Crystal Harris

  • Hugh Hefner And Crystal Harris

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  • Hugh Hefner With Chyna

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  • Hugh Hefner And Crystal Harris

  • Hugh Hefner And Barbi Benton

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  • Hugh Hefner And Crystal Harris

  • Hugh Hefner And Crystal Harris

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