The Casamigos Halloween party was the highlight of last night's celebrity events, with two celebrities, Paris Hilton and Jessica Alba, paying tribute to Britney Spears and cheering on the newly best-selling author without uttering a word. Without saying a word, they cheered her on.

Hilton and Alba arrived at the party separately, but both appeared in the style Spears wore in the iconic music video for her 2003 hit "Toxic," E! Hilton, a longtime friend of Spears, wore a teal flight attendant costume (her husband Carter Ream also attended the party dressed as a pilot). To show her support for Spears, Hilton took to Instagram to model the outfit, walking around while Hilton lip-synced the line "It's Britney, bitch." to the intro of Spears' 2007 hit "Gimme More" and posted a video of him doing the same.

"In honor of our queen," Hilton captioned her post.

Alba wore a glittering nude bodysuit, reminiscent of another look from the "Toxic" video. She was accompanied by Baby2Baby co-CEO Kelly Sawyer Patricof, who was on hand for Spears' 1998 "... Baby One More Time" video, in a schoolgirl costume.

The Halloween party took place just three days after Spears released The Woman in Me, a bombastic memoir in which she praised Hilton. In it, Spears says that her party days with Hilton in the early 2000s were not as "wild" as the media "bluster" made them out to be. Spears also praised Hilton for being "so helpful" to her when she was "suffering" from her breakup with Kevin Federline, writing that "she was so kind to me."

In addition to Hilton and Alba, Casamigos' Halloween party was attended by Justin Bieber, Jodi Turner-Smith, Megan Fox and Machine Gun Kelly, Cindy Crawford and husband Rande Gerber (who co-founded Casamigos), daughter Kaia Gerber and her boyfriend Austin Butler, among others.