Rihanna and Katy Perry

(Photo by Larry Busacca/Getty Images For The Recording Academy)

Cast of Friends

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Jon Favreau and Vince Vaughn

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Nicole Kidman and Naomi Watts

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Matt Damon andBen Affleck

(Photo credit should read HAL GARB/AFP/Getty Images)

Salma Hayek and Penelope Cruz

Photo credit should read HECTOR MATA/AFP/Getty Images

Jennifer Aniston and Courtney Cox

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Brad Pitt and Geoge Clooney

Photo credit should read ALBERTO PIZZOLI/AFP/Getty Images

Miley Cyrus and Taylor Swfit

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Tobey Maguire and Leonardo DiCaprio

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Kate Hudson and Liv Tyler

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Jessica Biel (L) and Jennifer Garner

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Jwoww and Snooki

. (Photo by Jason Merritt/Getty Images)

Victoria Beckham and Eva Longoria

(Photo by John Shearer/Getty Images for InStyle)

Tina Fey and Amy Poehler

Photo by Jason Merritt/Getty Images