Actor Joseph Gordon-Levitt let slip that Lady Gaga will make an appearance in the upcoming Robert Rodriguez film, Sin City: A Dame To Kill For, set for release in August 2014. The news was revealed while Levitt was promoting his new film, Don Jon, out September 19th. This will be Gaga's second major film appearance, as she will be starting in Machete Kills, which is out in October 2013. Check the video interview below (Gaga starts at 5:29)