Katy Perry throws '50s-themed birthday party

Katy Perry stepped back in time to the 1950s on Saturday (29Oct16) as she celebrated her 32nd birthday with a sock hop-themed party.

The pop superstar turned 32 on 25 October (16), and on Saturday, she was joined by boyfriend Orlando Bloom and pals including Kate Hudson, Jessica Alba, Cara Delevingne, Jessica Chastain, and Tobey Maguire's estranged wife Jennifer Meyer for the '50s teen dance party.

The Los Angeles bash was decorated to look like a school party for Hudson High, taking its title from Perry's real family name, and featured a traditional jukebox, pinball machines, a hula-hooping dance off, a pie-eating contest, an oversized Twister board on the dance floor, and more.

"It was insane," a source tells UsMagazine.com. "There was a huge marching band at the valet. The whole place was decked out as Hudson High. The evening started with drinks in an area that was converted into a diner with pinball machines and '50s waiters and diner tables. And then the band came in and marched upstairs, and guests went up to the main hall where there was a cafeteria serving lunch food."

Birthday girl Katy, real name Katheryn Hudson, dressed up in a black and yellow skirt suit with matching blouse and a bright yellow beehive-style hairdo as she played principal for the day, complete with a name tag reading, "Principal Hudson".

Orlando got in on the school spirit by going as a sports jock, wearing a red letterman's jacket and black shorts.

It was the second consecutive night of dress up for many of the stars - Katy and Orlando had spent Friday night (28Oct16) attending her namesake Kate Hudson's annual Halloween party, which they attended as presidential rivals Hillary Clinton and Donald Trump, respectively.