"So I'm prepping for a 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 -- like these pants barely fit me," Cooper told Ellen DeGeneres on Monday.
"So I wore the tuxedo I wore to the Golden Globes. I just sort of threw it in the bag and brought it and went to Washington, D.C. Then I'm getting dressed like 10 minutes before I was supposed to go, and literally the pants go up to like here," the American Hustle star said, gesturing to his upper thigh.
"I just started laughing, actually. This is hilarious, I'm going to meet the President. So I had to go commando number one cause there was no room at all," Cooper added. "I couldn't stand up really."