Bill Clinton's 65th birthday celebration and 'Decades of Difference' concert brought out a lot of stars, including Bono, Usher and, perhaps the highlight of the evening, Lady Gaga.

In what's being dubbed her "Marilyn moment," the pop sensation broke out a performance of 'Bad Romance,' substituting "Bill" for "bad" in the intro for the former president.

"I thought, ‘My God. I get Lady Gaga, and I will have a heart attack celebrating my 65th birthday,'" said Clinton about the star, who looked like a modernized version of Marilyn Monroe with wavy blonde hair and a nude-colored ensemble. He later announced, "I am the only person in history who got to be President and then had a post-presidential birthday party attended by both Lady Gaga and the Secretary of State."

Probably the most remarkable aspect of her performance, however, was that despite the audience filled with government officials, Gaga still dished out a number of sexual innuendos and F-bombs.

[via PopCrush]