Since 1993, the slogan “got milk?” has been ripped off countless times by amateur self-marketers — this blog entry’s headline is just one of millions (heh). I’ve also got a T-shirt in my drawer printed up by a rapper in Locker Partner’s Kansas City hometown that has a watermarked gorilla face on it and the phrase “Got Grit?” emblazoned across it. (I’m not sure what it means, but apparently “grit” is important in said rappers’ personal lexicon.) Need a quick headline or campaign slogan for your bid for student council vice-pres? This age-old catchphrase got you covered. Just don’t expect points for originality.

Well, never the type to do anything halfway, Goodby, Silverstein & Partners — the creators of “got milk?” — recently unleashed a new campaign for the California Milk Processing Board that shows not only the agency’s plugged-in comedic sensibilities but also serves as an excellent example of viral marketing across social media platforms. Because, after all, if your job is to promote a product or brand, then the whole point of social media is to get your content viral. Social media is by its nature viral.

Behold, White Gold. Jumping on the wave of Guitar Hero-inspired nostalgia for the days of fist-pumping, spandex-wearing glam metal, GSP created a sci-fi-rock-opera ad campaign for milk. At the center of the story is White Gold, a washed-up rocker who becomes a galactic celebrity thanks to milk. Looking like Ted Nugent and sounding like the guy from Electric Six, Mr. Gold chugalugs cow juice, shreds solos on a milk-filled guitar and sings about the benefits of calcium.

The heart of the advertising-as-entertainment campaign is The Battle for Milkquarious, an over-the-top, 20-minute, musical mini-epic that owes a lot to Flash Gordon and The Darkness. But the scope of the campaign is much broader. The advertisers created an official MySpace band page for White Gold with full-length songs, a Facebook fan page, an iTunes account with songs from the flick and a YouTube channel with trailers and TV spots that aired in California.

With all that high-production “milkdonculous”-ness, how can it not go viral?

Visit Goodby’s site for a a video primer on the campaign, and let us know what you think in the comments.

Got legs?