When you work for a large company -- the sixth largest independent advertising agency in the U.S., for example -- and your two offices unite for a Christmas holiday, there's always the chance of awkwardness. The two teams may keep to themselves, high school style. Or there could be an underlying rivalry that makes the whole experience tense.

But when the Tampa office of 22squared, the agency that brought you "Hello, Future" and "Pet the Kitty" banner ads, arrived in Atlanta for the holiday party, they were greeted enthusiastically, reports AgencySpy. By a flash mob.

It started with just two ladies, strutting toward their suitcase-saddled colleagues. But soon, a few dozen employees were dancing in sync to a medley of Usher's "Yeah," Outkast's "Hey Ya!," and Soulja Boy's "Crank That."

As the song finally fades, and the Tampa employees are left with disbelieving grins, the Atlanta team erupts into cheers, and waves two signs: "Welcome to Atlanta" and "Where the Playas Play."