The ad, which quietly appeared in February as part of a viral campaign, has attracted little notice thus far, but because it comes from a highly respected American brand, it seems to mark some kind of cultural tipping point, where pornography has soaked so far into the fabric of mainstream culture that it's no longer seen as a stain. The phenomenon, known as porn creep, is also evident in ads from such companies as American Apparel, Carl's Jr. and Quiznos. This is a family website, so you can Google those ads on your own. (See the best and worst Super Bowl ads of 2009.)

So far, there hasn't been much pushback. Even anti-pornography activist Donna Rice Hughes was not shocked that Anheuser-Busch, which makes Bud Light, would go there. "The line has gotten really blurred," she says. "There's a whole generation that has been pornified. They don't think it's a big deal. Budweiser's tapping into that." (Read 10 questions with Hugh Hefner.)