AceShowbiz -

Bradley Cooper opted to leave his underpants at home before meeting President Obama. The Rocket Raccoon of "Guardians of the Galaxy" revealed to Ellen DeGeneres that he went commando when attending a White House state dinner earlier this month because he had gained weight to prepare for his new role and his outfit was too tight.

"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," he began explaining his faux pas during an interview on "The Ellen DeGeneres Show" Monday, February 17.

"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," he shared, motioning to his upper thigh.

"I just started laughing, actually, [like], '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. I did. I had to," he continued. "I couldn't stand up really," he said, before adding, "It was a nightmare. But I made it through."

Cooper, 38, was joined by his girlfriend Suki Waterhouse to the state dinner on February 11 in Washington, D.C. He was recently spotted supporting the 22-year-old model at London Fashion Week as she hit the runway in the Burberry autumn/winter collection.