01/04/2011 08:03 am ET | Updated May 25, 2011

Ashton Kutcher & Natalie Portman Have Nude Sex Scene In 'No Strings Attached' Trailer (VIDEO)

Maybe they should call it 'No Clothes Attached.'

After a more or less innocuous, public audience trailer advertising what seemed like a run of the mill romantic comedy, Ashton Kutcher and Natalie Portman go risque in the new red band trailer for their new film, 'No Strings Attached.'

Portman and Kutcher play best friends that begin to sleep with each other... to predictable, yet potentially surprisingly funny results. One thing's for sure: those results are racy.

The film co-stars Mindy Kalig of 'The Office,' Jake M. Johnson of 'Paper Heart,' Greta Gerwig of 'Greenberg,' and Ludacris. It hits theaters January 21st.