Every once in a while, our favorite starlets like to show a little extra affection for each other. Sometimes these kisses are innocent pecks on the cheek, while other times they're full-on provocative lip-locks. (Such smooches have even been celebrated in songs like Katy Perry's 'I Kissed a Girl'!)

We were shocked by some of these stars going in for a little action (but not so surprised by some of them). From the iconic Britney Spears-Madonna-Christina Aguilera kisses to some famous movie hook-ups, we've got it all immortalized in the photos and videos of celebrity girls kissing girls below.

Britney Spears and Madonna

Britney Spears Madonna
Frank Micelotta, Getty Images
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Rihanna and Katy Perry

Rihanna Katy Perry
Jeff Kravitz, FilmMagic
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Miley Cyrus and Cara DeLevingne

Miley Cyrus Cara
Twitter
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Sandra Bullock and Scarlett Johansson

Scarlett Johansson Sandra Bullock
Jeff Kravitz, FilmMagic
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Brittany Snow and Sophia Bush

Brittany Snow Sophia Bush
YouTube
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Miley Cyrus and Katy Perry

Madonna and Christina Aguilera

Madonna Christina Aguilera
Scott Gries, Getty Image
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Britney Spears and Rihanna

Britney Spears Rihanna
Ethan Miller, Getty Images
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Natalie Portman and Mila Kunis

Natalie Portman Mila Kunis
YouTube
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Selma Blair and Sarah Michelle Gellar

Selma Blair Sarah Michelle Gellar
SGranitz, WireImage
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Heather Morris and Naya Rivera

Heather Morris and Naya Rivera
YouTube
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Mischa Barton and Olivia Wilde

Mischa Barton Olivia Wilde
YouTube
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Meryl Streep and Sandra Bullock

Meryl Streep Sandra Bullock
Kevin Winter, Getty Images
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Amanda Seyfried and Megan Fox

Amanda Seyfried Megan Fox
YouTube
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Alanis Morissette and Sarah Jessica Parker

Alanis Morissette and Sarah Jessica Parker
YouTube
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Courteney Cox and Jennifer Aniston

Nikki Reed and Evan Rachel Wood

Nikki-Reed Evan Rachel Wood
YouTube
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