When Kim Kardashian needed a friend to help her with her Halloween costume, Jonathan Cheban was like, "I got you babe!"

He and the Keeping Up With the Kardashians star dressed up as the late Sonny Bono and pop superstar Cher for the 2017 Casamigos Halloween Party. Kim wore a yellow, long sleeve, bohemian-style crop top and flared pants with sparkling embellishments. Jonathan wore a wig and fake mustache and plum checkered tux. She also sported a long, dark brown wig—similar to her own natural hair—over her platinum blond locks.

The real Cher was very impressed with Kim and Jonathan's tribute.

"@KimKardashian Woke To See You Are Me 4...You Look BEAUTIFUL Little Armenian Sister," she tweeted. "Dream Of India Is Perfect 4U & @BobMackie at his best."

Kim seemed relaxed and in a great mood at the party, E! News has learned. She chatted with model Kelly Sawyer, who was dressed as a cheerleader, as well as other pals. After a few minutes outside, Kim and Cheban linked arms and walked inside the party, did a small lap and left, E! News has learned.

They later had a blast filming Snapchat videos of themselves lip-synching the former couple's 1965 hit "I Got You Babe" and Cher's 1998 dance song "Believe." 

Kim Kardashian, Jonathan Cheban, Halloween

Neilson Barnard/Getty Images for Casamigos Tequila

Sonny Bono, Cher

Ron Galella/WireImage

The Casamigos Halloween party is an annual bash thrown by the company owned by George Clooney and Rande Gerber. The latter attended Friday's event, which had a '70s disco theme, with wife Cindy CrawfordGeorge's wife Amal Clooney and kids Kaia Gerber and Presley Gerber, who brought friends with them. Amal and the Gerber family wore '70s-style outfits. Amal sported a strapless, sparkling blue jumpsuit, large hoop earrings and round sunglasses and a large, afro-style curly wig.

Amal hung out with Cindy in a booth, had fun dancing to the disco music playlist and drank a Casamigos cocktail.

See photos of famous guests at the party as well as pics of other celebs celebrating Halloween 2017.

Ariel Winter, Halloween 2017

Michael Wada

January Jones, Halloween 2017

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Kendall Jenner, 2017 Halloween

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John Legend, Chrissy Teigen, Halloween 2017

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Heidi Klum

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Pink, Halloween 2017

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Maci Bookout, Halloween 2017

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Jessica Simpson, Halloween 2017

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Jessica Biel, Justin Timberlake, Halloween 2017

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G-Eazy, Halsey

Fergie, Halloween 2017

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Jessica Alba, Cash Warren, Halloween 2017

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Ariel Winter, Levi Meaden, Halloween

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Emma Robert, Evan Peters, Halloween 2017

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Wiz Khalifa, Izabela Guedes, Halloween 2017

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Sarah Michelle Gellar, Freddie Prinze Jr., Halloween 2017

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Jessie James Decker, Halloween 2017

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Tom Brady, Gisele Bundchen, Halloween 2017

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Khloe Kardashian, Tristan Thompson, Halloween 2017

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Carrie Underwood, Mike Fisher, Halloween 2017

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Ryan Lochte, Kayla Rae Reid, Halloween 2017

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Kendra Wilkinson-Baskett, Hank Baskett, Halloween 2017

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Natalie Dormer, Halloween

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Today, Halloween

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Amber Rose, Halloween 2017

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Tony Goldwyn, Kerry Washington, Bellamy Young, Halloween 2017

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Colton Haynes, Jeff Leatham

Rupert Thorpe

Rob Kardashian, Dream Kardashian, Blac Chyna, Halloween

Instagram, E!

Nicole Scherzinger, Halloween 2017

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Vanessa Hudgens, Halloween 2017

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Kelly Ripa, Ryan Seacrest, Halloween

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Tamra Judge, Halloween 2017

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Today, Halloween

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Good Morning America, Halloween, 2017

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Alessandra Ambrosio, Halloween 2017

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Halle Berry, Halloween 2017

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Paris Hilton, Halloween 2017

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Neil Patrick Harris, David Burtka, Halloween

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Holly Madison, Halloween 2017

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Hilary Duff, Halloween 2017

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Good Morning America, Halloween, 2017

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Matthew Morrison, Halloween

Vivien Best

Wiz Khalifa, 2017 Halloween

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Ariel Winter, Levi Meaden, Halloween 2017

Nate Weber / Universal Studios Hollywood

Naomi Campbell, Halloween

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Kristen Doute, Brian Carter, Halloween 2017

John Sciulli/Getty Images for Chivas Regal

Karlie Kloss, 2017 amfAR Fabulous Fund Fair

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JWoww, Halloween 2017

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Photos

See More From Stars Celebrate Halloween 2017

Shannen Doherty was spotted with husband Kurt Iswarienko. The actress, who recently battled breast cancer, looked fab in a short black bob wig, fishnet tights, short denim shorts and a black top and was laughing and smiling. 

Other celebrity guests included Buffy the Vampire Slayer and Gossip Girl alum Michelle TrachtenbergCourtney LoveMolly Sims and husband Scott StuberJon HammDavid SpadeRachel ZoeRachel RoySeth MacFarlaneSacha Baron Cohen (a yellow smiley face emoji) and wife Isla Fisher (a unicorn), Alessandra AmbrosioDerek Hough (teddy bear) and girlfriend Hayley Erbert (Wonder Woman), Russell Simmonsand Adrien Brody—who dressed up as a panda!

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