First Lady Michelle Obama greeted – and hugged – tourists for more than an hour, and their happy faces, shock and tears were all broadcast live on the White House's official website.
"Surprise," she told the stream of visitors. "Welcome to my house."
Clad in a black and white printed dress, and with dog Bo at her feet, the First Lady warmly greeted an array of people – from students to senior citizens – and engaged them in short, but personable, conversations about everything from her "Let's Move!" campaign ("Tell your grandbabies I said to eat your vegetables," she told one woman) to fashion ("I've never seen sparkly Uggs before," she told another).
Many visitors asked to pet Bo, and Obama indulged, telling them about the dog's good "temperament" and how they had hired a trainer when he was younger.
One young tourist was celebrating her birthday. "That's why I came down," Obama told her. "Have a very cool 13th birthday."
This isn't the first time that the First Lady has popped in to greet White House tourists, either. She's been known to meet visitors on the anniversary of her husband's Jan. 20 inauguration.