Kelly Clarkson and Brandon Blackstock Credit:

Best date night ever! Kelly Clarkson and fiance Brandon Blackstock got all dressed up to attend President Barack Obama's second inauguration in Washington, D.C., on Monday, Jan. 21. After the American Idol winner performed "My Country 'Tis of Thee" with the United States Marine Band, she did a quick costume change and attended the Commander-in-Chief's Inaugural Ball at Walter Washington Convention Center.

"Me and Brandon in our 'fancy' attire Fun night!" Clarkson, 30, tweeted a photo of the couple, who got engaged in December 2012 after nearly a year of dating.

"My dress barely fit in the car for tonight's festivities," the "Mr. Know It All" singer captioned a funny photo of herself crammed into a car. "I feel like Cinderella! Thank you Oscar De La Renta!"

And Clarkson had a great time celebrating at the ball. "Just partied at the White House . . . I kid you not, Michelle Obama stood up and got the party started . . ." she tweeted. "Seriously cool First Lady."

But the highlight of the singer's day was meeting Obama himself. "Maybe the coolest photo I've ever been in . . . ever," she wrote with a photo of herself shaking his hand. "What an honor to be a part of history! Obama's presence was powerful and his words unforgettable. It's a proud day for America!"