Rachel McAdams has offered to be an understudy in the 'Mean Girls' Broadway show.

The 38-year-old actress - who played Regina George in the 2004 cult classic - can't wait to see the upcoming stage musical version of the iconic film and joked she'd reprise her role on occasion if necessary.

Speaking to media at the Toronto International Film Festival (TIFF), she said: ''I really hope I get an invitation, yeah.

''I would love to see it. I'm so, so curious about it.

''I'll be the understudy. I just hope Regina George never gets sick.''

Regina will be played on stage by Broadway veteran Taylor Louderman and creator Tina Fey recently proclaimed her to be the perfect choice for the role.

She said: ''Taylor Louderman not only has this giant voice and great comic timing, but she instinctively understood the idea of Regina George, that there's power in making people come to you.

''She knows exactly when to play things really small, and there's so much power in it, and I think she's at times so wonderfully scary but so funny.''

Tina previously revealed her husband, Jeff Richmond, had encouraged her to adapt her movie for the stage.

She said: ''It came about years later, after seeing the stickiness that the movie had, and the fact that it's always on TBS and how it sort of wormed its way into everyday speech more than any of us expected.

''It was probably my husband, Jeff [Richmond], who said, 'You know what? This could work as a musical.' And I trusted him to know that, having that background.''

'Mean Girls' will open on Broadway on April 8, 2018.