by Chelsea StewartBuzzFeedBuzzFeed StaffI'm Chelsea, the Weekend Editor at BuzzFeed, where I cover everything from pop culture and politics to TV and celebrity news.

Kissing a famous actor might seem like a dream — but to these celebrities, it was anything but romantic. From bad breath and nerves to awkward dynamics or just plain discomfort, many actors found that smooching their co-stars wasn't nearly as glamorous as it looked onscreen. From Megan Fox and Rob Pattinson to Jennifer Lawrence and Will Smith, here are 19 actors who hated kissing their co-stars.

Rupert Grint and Emma Watson — Harry Potter and the Deathly Hallows, Part 2

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Rupert and Emma struggled to kiss each other because of their close friendship, which began when they were just kids.

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"It seemed like the most unnatural thing to do, to kiss this person I'd known since she was nine," Rupert told Attitude Magazine (via HuffPost). "It took a while to get into it and put our friendship aside." Emma admitted it was "like incest." "We both wanted it to be over equally as much as the other," she said. "He's like my brother."

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Matt Damon and Angelina Jolie — The Good Shepherd

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Matt hated kissing Angelina because it felt like kissing a sibling.

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"We're old friends, so it was like kissing my sister: really awkward, and generally awful," he told Reveal magazine. It was also "weird," given that Angelina was dating his good friend Brad Pitt at the time. Angelina, however, said their partners didn't mind at all. "The people we're involved with couldn't have cared less about that because they know us," she told ABC News. "You know, it's one of those things where it's like the least threatening person. … You know, good luck to you guys, I hope it's not too awkward."

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Kirsten Dunst and Brad Pitt — Interview with the Vampire

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Kirsten called kissing Brad "gross," as she was 11 and he was 29.

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"I hated it so much," she told Entertainment Tonight. "Because, I don't know—Brad was like on my older brother on the set. It's kind of like, kissing your brother ... It's weird, 'cause like, he's an older guy, and I had to kiss him on the lips, so it was gross."

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Dane Cook and Kate Hudson — My Best Friend's Girl

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Dane called Kate his worst onscreen kiss.

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"I did a movie with her, My Best Friend's Girl, and I think she purposely ate like a feast of onions before our scene," he told Watch What Happens Live. "I had to burn her on that one!" Kate later refused to comment on Dane, jokingly calling him "canceled."

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Kate Hudson and Matthew McConaughey — How To Lose a Guy in 10 Days and Fool's Gold

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Kate said Matthew was her worst onscreen kiss.

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"The thing is, every time I kiss McConaughey, it's like, I mean, it's like there's just something happening, and there's snot or wind, or things are just…like when we were kissing in the end of Fool's Gold, we're in the ocean; we, like, had the plane crash," she told Gwyneth Paltrow's Goop podcast with a laugh. "He just had snot all over his face." She also said their dynamic could feel "a little sibling-y," which didn't help.

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Alyson Hannigan and Jason Segel — How I Met Your Mother

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Alyson hated kissing Jason because he smoked.

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"It's like kissing an ashtray," she said, according to Digital Spy. "And he's trying to be polite by having gum or mints, but it doesn't help."

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She even tried a bet to get him to quit: $10 every time he had a cigarette, but it only worked temporarily. "He quit cold turkey for about a year," she shared. "It was fantastic but then ... he got stressed out and he started smoking again."

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Thandiwe Newton and Tom Cruise – Mission Impossible 2

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Thandiwe described kissing Tom as “slightly icky and sort of wet."

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She added, "When my husband saw the movie, he whispered to me, 'Are you alright sweetheart? It must have been awful doing that scene.' I don't know whether he was joking or not."

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Megan Fox and Amanda Seyfried — Jennifer's Body

Both actors found their onscreen kiss "very stressful."

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"I remember Amanda and I were horrified that we had to make out," Megan told Variety. "Her more so than me. I was slightly more comfortable being able to do it. She was not excited about having to film that scene at all."

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Actors Who Hated Kissing Their Co-Stars