Sean Penn and Scarlett JohanssonSean Penn and his rumored girlfriend Scarlett Johansson caused quiet a stir with their public display of affection at the annual White House Correspondents Dinner over the weekend.

While Johansson came to the event with her brother Hunter, she was soon seen at the side of rumored live-in boyfriend Penn who attended as the guest of a media outlet.

The New York Post reports that Penn raised some eyebrows when he refused to put his hand over his heart when everyone stood up to sing "The Star-Spangled Banner."

Later, despite the presence of President Barack Obama, other celebrities and members of the media, an eyewitness told UsMagazine.com that Penn, 50, and Johansson, 26, were engrossed in an 'intense' makeout session.