But when Levi's director of marketing Doug Sweeney called McBride and Cutwater director of broadcast/content production Jennifer Golub early in the year, it was more than friendly. Sweeney was practically Cutwater family. He'd worked at Chiat\Day as managing director for five years, mostly on Adidas, and had developed a friendship with Cutwater's new president, Walter Smith, when Smith worked on Saturn at Hal Riney.

"We're old friends," said Golub of Sweeney. "He knows how we work and he wanted to do some exploration. Doug was looking for an opportunity to experiment, add expression to the brand." McBride said the brief from Levi's was simply "a framework -- use the idea of 'unbuttoned' as an expression of individualism."

McBride said it's OK by him, if despite his original intention, the viral moves to television under BBH's strategy "as long as it started where it needed to start," over the Web.

Smith agrees: "It's all changing so fast. As long as the creative is cool and watchable and part of a social context, the lines [between viral and commercial] are colliding and blurring, and not mutually exclusive."

That the viral resonated with young men has not been lost on Levi's Cameron, who said awareness of 501s is higher among older men than youths. "The future of any brand requires relevance to that target," Cameron said. "We've introduced so many products -- skinny jeans, baggy jeans -- we haven't supported 501s properly. It's time to talk about them as the mack daddy of jeans."

Levi's ad spend was about $70 million last year, with roughly half of that going to 501, according to Nielsen Monitor-Plus. Cameron declined to say how much Levi's was putting behind the global push.

According to Tom Julian, president of The Julian Group, a brand consultancy in New York, it's a necessary effort for a brand that has lately been challenged in the global denim marketplace. Julian said that the Levi's brand resonated during the '60s and '70s, but not so much in recent decades. "They continue to have heritage with American-made denim," he said. "But it's been a hard reinvention with the competitive state of the changing retail landscape and shifting consumer fashion and style preferences."

The popularity of the virals may be a good start, Julian said. "It is not a surprise that the viral has tracked. Men of all ages have embraced online experiences, but the younger consumer is more astute," he said. "I would suspect that Levi's would need global marketing with a strong local component tied to key retailers and dynamic cultural platforms."