AceShowbiz - Olivia Wilde is showing off some skin on her birthday. The "Don't Worry Darling" actress/director posted a photo of her "shameless" butt tattoo on her social media page to celebrate her 39th birthday.

The star, who actually turned 39 years old on March 10, kept the celebratory vibes going on Wednesday, March 22. Making use of her social media account, she posted a black-and-white photo of her posing with her back to the camera. She could be seen wearing a white string bikini top and a thong bottom that revealed a dragon tattoo on the top of her right butt cheek.

"39 and feeling fine," Olivia wrote in the caption. The "Booksmart" director went on adding, "Thanks for the birthday love. I milked it for way too long and it's been great. Here's to whatever's next. Probably not another tramp stamp but who knows. #shameless #howdareshe #thehorror [heart emoji]."

While her dragon tattoo might come as a surprise to some fans, Olivia actually spoke about the ink in a 2017 interview with Craig Ferguson. "I have one really bad one," she said when the late-night host asked if she had any tattoos, admitting that she got "a tattoo of a dragon" when she was just 13 years old.

"You hand over cash, they'll tattoo a cat," Olivia said about her shocking underage experience, adding she "was in New York City and I thought it was a great idea, it had a lot of meaning at the time but now it's hideous."

As for the location, Olivia was hesitant to admit where the dragon was located, eventually revealing it was on her "lower, lower, lower back." The "Babylon" star then added, "It's not a tramp stamp!" before giving a hint, "It's over to the right. It's an ass stamp, which is probably a lot classier."