First Look: 'Sisters' Star Tina Fey Jokes 40-Year-Olds Need to Party More Than Teenagers

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Amy Poehler and Tina Fey have reunited for the upcoming comedy, Sisters, and ET has your very first look.

In the movie, the two funny ladies play adult siblings who throw one last, epic party before their parents (James Brolin and Dianne Wiest) sell their childhood home.

Unlike 2008's Baby Mama, which the two co-starred in, Amy plays the responsible one, while Tina portrays the trainwreck.

WATCH: Amy Poehler and Tina Fey Reunite in Hilarious 'Sisters' Trailer

"People in their 40s need that party a lot more than people who are 19," Tina says in a behind-the-scenes interview. "They are letting off steam about something."

Sisters, also starring Maya Rudolph, Ike Barinholtz and John Cena, opens Dec. 18.