Joanne Bradford, the hard-charging SVP who oversaw North American revenue and market development at Yahoo , quit to join Demand Media in March. Now other Yahoo executives are following her to the high-flying start-up.

This week, New York City-based Yahoo VP Erika Nardini walked out the door with a story in tow–and a boon for her mother, who bet on the circumstances surrounding her departure. “When I told my mom I was resigning from Yahoo, she was semi-interested in where I was going,” Nardini explains. “What really interested her was the gamesmanship.”

Nardini’s mom, who lives in Stowe, Vermont, used to teach business law (hence her interest in corporate machinations) and today spends her time “playing copious amounts of Mahjong,” says Erika, 35. The Mahjong ladies typically bet 25 cents a round. But they were so intrigued by Erika’s decision to leave Yahoo that they raised the stakes on this question: Would Erika, when she quit, be escorted out of Yahoo?

“I don’t think they do that here,” Nardini told her mother.

Well, on Tuesday, at Yahoo’s mid-town Manhattan offices, Nardini was indeed officially escorted out as she toted a Whole Foods paper bag stuffed with her extra shoes, a blazer and a raincoat.

“I sent my mother a text at 4:55 p.m. as I was walking out,” Nardini recalls.

Her mom’s reply: “‘Yes! I’m in the money!” She won $25.

What’s luring Nardini and other Yahoos, including former sales VP David Oliveira and former senior director of ad sales Pete Hagerty, to Demand Media? “It’s a very nimble company that’s poised for growth,” says Nardini, who will be SVP of sales and marketing at Demand. She was VP of packaging at Yahoo and before that, she worked with Bradford at Microsoft . Bradford is now Demand’s chief revenue officer.

Demand is the creation of Rich Rosenblatt, who sold MySpace’s parent, Intermix Media, to News Corp. in 2005. An online content factory that churns out articles and videos cheap and fast, Demand leaves consumers clueless about how its media is manufactured.

How will Nardini market a company that has, so far at least, thrived by flying under the radar? “That is the question, quite honestly,” she admits. Something to challenge her, come Monday.