Miley's birthday cake was in the shape of a giant pizza Credit: Courtesy Miley Cyrus

Happy Birthday, Miley Cyrus! The now 22-year-old pop star went all out for her birthday celebrations in Los Angeles on Saturday, Nov. 22, hiring out the soon-to-be-opened Beacher's Madhouse for a "Miley's Twisted Mind" themed bash.

Guest of honor? Cyrus' new boyfriend Patrick Schwarzenegger, who, a source told Us Weekly, "brought a bunch of his guy friends who were tripping out on this party, they have never seen anything like it!"

In typical Cyrus fashion, the party (organized by showman Jeff Beacher, nightlife impresario behind the wacky Beacher's Madhouse) had wild and crazy decor and entertainment on tap, as well as Stillhouse cocktails.

The "Wrecking Ball" singer wore a neon pink and green cut-out dress with a matching pink, fluffy, cropped jacket. Her birthday cake looked like a giant pepperoni pizza (as she displayed in a photo, shared via Instagram) and the main entertainment was a mechanical bull, outfitted as a giant penis.

"Miley and other guests took turns riding on it," another source tells Us. "There was also a photo booth where you got on a bed. And there were lots of psychedelic decorations and black light."

As previously reported, Schwarzenegger and Cyrus have been seeing each other since last month. "They have been friends for a long time," one insider told Us. "They have a ton of common friends so they have run in the same circles for years."

And judging by their appearance at Cyrus’ birthday bash, things are going well. “Miley and Patrick were hugging and dancing together," the party source continued, adding that her new beau "blended in well and was with her much of the time."