Natalie Portman is defining on-screen hotness in the 21st century. First she sizzles in a lesbian love scene in “Black Swan.” Now she’s switch-hitting. In her latest film, “No Strings Attached,” she has a hot love scene with Aston Kutcher.

The film co-stars Mindy Kalig of “The Office,” Jake M. Johnson of “Paper Heart,” Greta Gerwig of “Greenberg” and rapper Ludacris.

Portman, who plays Emma and Kutcher, who plays Adam, are best friends. Ultimately, they let their passions get the better of them, and end up in bed together.
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The premise of the romantic comedy is can “sex friends” still be “best friends.”

To maintain their friendship, they make a pact to keep their relationship “no strings attached,” meaning no jealously, no fighting, no flowers, no cloying affection.

The relationship is purely sexual and judging by a new trailer, they leave little to the imagination in the movie.

This is the second trailer released for the movie. The first was designed for a public audience; This trailer bears a restrictive rating and a so-called red band opening. Less risqué trailers have a green opening.

It hits theaters January 21st.