At the star-studded White House Correspondents' Dinner on Saturday, where Capitol Hill political battles were put on hold for jokes, two secretive A-listers were seen acting like a bona fide couple.

Scarlett Johansson, 26, brought her fraternal twin, Hunter (pictured), to the formal affair. But the Washington Post reports that she was soon fraternizing with rumored live-in boyfriend Sean Penn, 50, who attended as the guest of a media outlet.

In a ballroom packed with media professionals, the two stars must each have known their every move would be scrutinized.

After the main course (steak and scallops), Johansson reportedly left her table to seek out Penn, and whispered in his ear before the two slipped out of the banquet room for a smoke break.

The Post claims Penn eventually gave his rumored paramour his tuxedo jacket to keep her warm; the couple were witnessed holding hands as they left a D.C. party later that night.