Does Kristen Stewart wear boy underwear? Kristen Stewart stripped down to just her bra and underwear for a skinny dipping scene on the set of "Sils Maria," but don't expect anything lacy or floral.

Kristen Stewart was photographed in a pair of white boyshort underwear and a plain black bra, before filming a skinny dipping scene with co-star Juliette Binoche on September 23 in Switzerland.

Check out the photo here.

Us Weekly reports that Kristen Stewart, who was sporting a tattoo below her right elbow for the role, wore a black bra and white boy shorts underwear for the scene, while Binoche, 49, appeared to go completely nude.

The two ladies were seen smiling as they went swimming in a lake.

"Sils Maria" tells the story of an aging actress (Binoche), who stars in a revival of a play that made her famous, but opposite the young role (played by Chloe Grace Moretz) she once had, Us Weekly writes. Stewart will play a supporting part as Binoche's assistant in the film.

"It takes two very particular people to have that relationship be functional -- one that services the other -- because Juliette Binoche is playing the actress that I assist, and she is one of the most powerful women I think I've ever seen in film," Stewart told WWD in July. "I'm going to try desperately to not be squashed by a woman like that, and it's not going to be an easy thing."

Interestingly, Bionche starred opposite Stewart's ex-boyfriend, Robert Pattinson, in the 2012 film "Cosmopolis."

Stewart and her "Twilight" co-star ex-boyfriend ended their longtime romance back in May.

"She's just been focusing on filming," an insider told Us Weekly about Kristen and her current love life.