Tina Fey.

Tina Fey Admits She Was a 'Mean Girl' in High School

No wonder Tina Fey penned the big screen comedy "Mean Girls." The actress recently admitted she was the mean girl back in high school, perhaps giving her tons to pull from to write the 2004 hit film.

"I was, I admit it openly," she told Net-a-Porter's The Edit. "That was a disease that had to be conquered."

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Fey, 45, said that later on in life she realized why she became a bully.

"It's another coping mechanism," she said. "It's a bad coping mechanism, but when you feel less than ... in your mind it's a way of leveling the playing field. Though of course it's not. Saying something terrible about someone else does not actually level the playing field.

"If I meet a girl of 14 or 15 today who is that kind of girl, I am secretly, in my body, afraid. Even though I'm 45," she quipped.

Being mean wasn't Fey's only coping mechanism. The actress said she also used comedy as a way to cope with her personal issues.

"For me it was about hitting age 13 and realizing, 'OK, I'm not going to glide by on looks. I'm a normal-looking person, but that's not going to be where my bread is buttered.' The desire to be funny -- because you are never actually quite sure if you really are funny -– is a coping mechanism, another way of ingratiating yourself," she said.

It's a good thing Fey used comedy to cope, especially since she relied heavily on those skills to craft knee-slapping funny moments in her latest film, "Sisters." She portrays the onscreen sister to fellow comedienne, Amy Poehler, in the film, which follows the two as they travel back to their childhood home. Although the sisters are supposed to be cleaning out their shared bedroom after the home sells to a new family, instead they throw one last epic party.

Fey couldn't help but gush about her friend and co-star.

"Amy is very warm, a great person to have on your team in any capacity," she said. "We work together best -- on 'Sisters,' or presenting the Golden Globes -- by doing our own thing next to each other. I do wonder, if we tried to do five years on a series together, if it would be like, 'Wait a minute, which one of us is the boss?' Because, truthfully, I think we are two Alphas."

The film also stars Fey's fellow "Saturday Night Live" alum Maya Rudolph and Bobby Moynihan along with wrestler John Cena.