Jennifer Aniston films "We're the Millers" in Wilmington, North Carolina on August 20, 2012. Credit: Splash News

Is it time for the bachelorette party?

Newly engaged actress Jennifer Aniston flashed her bra to her fake husband, Jason Sudeikis, on the set of We're the Millers Monday. In the new film, the 43-year-old plays a prostitute whom Sudeikis' pot dealer character hires to pretend to be his wife as he attempts to smuggle 1,400 pounds of marijuana across the country. 

During filming Monday in Wilmington, North Carolina, Aniston unbuttoned her sleeveless blouse to reveal her nude-colored bra to her costar. And while the actress plays a faux spouse to Sudeikis, 36, she's preparing to play the real-life role of wife to Justin Theroux

After 18 months of dating, Theroux, 41, popped the question to Aniston on Aug. 10. "Justin Theroux had an amazing birthday Friday, receiving an extraordinary gift when his girlfriend, Jennifer Aniston, accepted his proposal of marriage," Theroux's rep said in a statement to Us Weekly on Aug. 12.

When Theroux presented his Wanderlust costar with the ring, "Jen cried," a confidant told Us. "The proposal was simple. He was surprised she said yes, but he is so happy."

Aniston has been wearing a wedding band on the We're the Millers set, but it appears to be for part of her character's costume and not her engagement ring from Theroux.