Oprah Winfrey  stunned the crowd gathered at the annual luncheon for the N Street Village, a Washington-based charity benefiting homeless women, with one of her patented “you get a caaaaar!” moments.

The media queen, who was the keynote speaker at the Ritz-Carlton event on Thursday, picked up a pledge card and filled it out in dramatic fashion: a promise of a $1 million donation. The crowd, of course, went nuts.

“Everyone absolutely went wild,” says one attendee.

N Street Village Executive Director Schroeder Stribling joined Winfrey onstage, waving the many-zeroed card aloft.

The gift was no scripted stunt. Board member Allison Kaminsky Putala tells us that organizers had no idea what was coming, and that they were just as shocked as the crowd. “We are obviously beyond thrilled,” she said.

The organization has previously harnessed star power to help its mission of providing shelter and other services to homeless and low-income women — actor Richard Gere has pitched in on fundraising efforts, too.