LaPlante, 22, told Newsweek about the celebration that took her by surprise. "Thinking I'm going to have a basic bachelorette party," she captioned ... also said that the theme was apt for her.

Swift herself donned a black Balenciaga minidress with a sparkly halter detail for the party, grinning in photos with her signature red lipstick. The venue was decked out with theme details ...