Bradley Cooper
Actor Bradley Cooper arrives at the 86th Academy Awards nominees luncheon in Beverly Hills, Calif., Feb. 10, 2014. Reuters/Mario Anzuoni

“American Hustle” star Bradley Cooper went commando to the state dinner hosted by President Barack Obama in honor of French President Francois Hollande at the White House.

Cooper revealed on Monday’s episode of “The Ellen DeGeneres Show” that due to a recent weight gain for a role, the actor had to skip wearing anything underneath his pants, in order to fit into them.

"I'm prepping for this new movie and I'm trying to gain weight fast, so I've gained about 15 pounds in four weeks and nothing fits me anymore," Cooper said. He aims to put on a total of 35 pounds to play a U.S. soldier, Chris Kyle, in “American Sniper.”

“So I wore the tuxedo I wore to the Golden Globes,” he continued. “I just sort of threw it in the bag and brought it and went to Washington D.C. and then I’m getting [dressed] like 10 minutes before I was supposed to go… I just started laughing, ‘Actually, this is hilarious, I’m going to meet the President.’”

The 39-year-old Oscar nominee said that his pants were so tight that he couldn’t wear anything underneath them.

“I had to go commando… ‘cause there was no room at all,” Cooper added. “I did. I had to. And you’re sitting there and it’s a lot of getting up [to greet people]. You know what I mean? And I couldn’t stand up, really.”

The actor said that due to restrictions in his trousers he had to greet every person standing side ways.

“And you have to walk up the stairs and it was a nightmare. But I made it through,” he said.

Check out the video here: