In her new movie, "Horrible Bosses," the queen of romantic comedies sheds her girl-next-door image to play a "sexually aggressive" dentist who harasses her male assistant, played by Charlie Day.
The part required Aniston to bare all, including a reported topless scene, a first for the actress, and to go right to the dark side with bad language and all.
"That's the sad part, that I was kind of comfortable," Aniston told "GMA" of the fun she had playing the role. "It was sort of a dream to just live in that skin and be able to say those words."
Later this fall, Aniston could also appear topless in the film in which she met Thoreaux, Judd Apatow's "Wanderlust." Aniston and Paul Rudd play a couple who drop out of the rat race to become hippies.
Aniston not only rips off her shirt but smokes pot and has a threesome, according to HollywoodLife.com.
Aniston says she doesn't feel Hollywood pressure to keep her body, also featured on the July cover of Marie Claire magazine, hot, but she does work at it.
"I do spinning, yoga and also circuiting. You sort of keep it moving," she told "GMA."
Aniston has shown she's not afraid to show some skin to promote a product (her fragrance line last year) or herself, for that matter (the cover of GQ in January 2009).
The actress also has a new ad out for SmartWater – this time she's posing next to a bottle of the designer water, without any clothes.
"I feel better when I'm fit," Aniston told "GMA." "Something about being able to just move that I love. It changes your energy and your spirits."
ABC News' Luchina Fisher contributed to this story.