As a late October baby, Katy Perry takes Halloween seriously. She threw herself a hilariously authentic 1950s-era high school sock hop birthday party on Saturday night — after she basically already won the holiday with her Hillary Clinton costume on Friday.The singer, who turned 32 on October 25, documented the whole thing on Instagram Stories. Donning a mile-high lime-green beehive, Perry was dressed as the strict principal of Hudson High School (named for her real last name). Guests were greeted by a marching band, vintage cars and a school bus.Bands performed period-appropriate music inside as cheerleaders twirled their batons. Marilyn Monroe and Elvis Presley came back from the grave to sing for everyone. Dinner was served cafeteria-style on metal trays. Then there was a giant game of Twister, which we really wish we could see play out for more than a few seconds. As Kate Hudson posted on her own Instagram Stories, there was a Stand By Me-style pie eating contest we really don't need to see any more of.Of course, there were plenty of guests dressed up to match the theme, including Perry's BF Orlando Bloom. He traded Friday's Trump costume for a short-shorts-wearing jock getup. Hudson dressed as what we assume is some kind of artsy rebel student, which went perfectly with the "Detention" classroom set up for photos. Peruse the slideshow for more.