What's Michelle Obama doing for fun these days? Hint: It involves rap.

Sometimes a girl just wants to have fun – even (or maybe especially) when she’s first lady of the United States.

Aside from vacationing on Martha’s Vineyard with her family this week, Michelle Obama has been doing a lot of that lately. She posted a selfie of herself and dog Bo on Twitter and Instagram last weekend. She danced during her kids’ “state dinner” last month. And who can forget her doing the Dougie in February on “Late Night with Jimmy Fallon,” where she demonstrated “the evolution of mom dancing”?

Now Mrs. Obama is breaking the mold again – with a rap album. She’s not singing, but she appears in one of the videos, called “Everybody.” The album – called “Songs for a Healthier America” – is inspired by the first lady's Let’s Move! campaign, and features big-name performers like Jordin Sparks, Ashanti, Run DMC, and Doug E. Fresh.

Song titles include “U R What You Eat” and “Veggie Luv.” The album is being produced by the Partnership for a Healthier America and Hip Hop Public Health Foundation, and will be released Sept. 30. The videos will be distributed to schools in New York City before wider circulation. Fighting childhood obesity is one of Mrs. Obama’s signature causes.

But there’s another real issue behind all her joyous activities: that life in the White House can feel like being in a “really nice prison.” She made that comment at the African First Ladies Summit last month in Dar es Salaam, Tanzania, in a public conversation with former first lady Laura Bush.

“There are prison elements to it,” Mrs. Obama said to laughter. “But it’s a really nice prison, so.…”

“But with a chef,” Mrs. Bush interjected.

“You can't complain,” Mrs. Obama continued. “But there are definitely elements that are confining.”

The White House as gilded cage is a theme that goes back to the start of the republic. The first first lady, Martha Washington, once wrote to her niece that she felt like a "Chief State Prisoner." But in the modern era, amid omnipresent technology, escaping constant public scrutiny can be an even more daunting task.

During her husband’s first term, Mrs. Obama – disguised in a ball cap and sunglasses – once pulled off a trip to a suburban Target, and went largely unrecognized. But since the start of the second term, Mrs. Obama has ramped up the fun quotient. Maybe with reelection out of the way, she feels she can cut loose a little bit more.

What her daughters – one a teen, the other almost – think of all this public fun is another matter. We suspect they’re mortified. But Mrs. Obama actually can dance. Certainly better than her husband.