"I feel much safer with girls, so I felt more comfortable kissing her in the movie than kissing any of the other people that I had to kiss," the 23-year-old actress tells MTV News.
Check out more photos of girl-on-girl action.
Seyfried was less at ease with the same-sex smooch.
"I think she was extremely uncomfortable. I don't think that -- I know that," Fox says. "She was not comfortable and there was a lot of laughing -- like, giggling fits that happened in between takes."
See pics of stars goofing off.
Fox has called the film (out Sept. 18) "so sexy" ... and she's pretty fond of her performance, too.
"I think I'm pretty sexy in it," she said at a Comic-Con event last month.
Check out Megan Fox's hottest red carpet photos of all time.
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