The process by which attitudes that oppose the status quo are co-opted by marketers for the purpose of selling consumer items. The result is painfully ironic because the resulting 1) increased consumerism and 2) assimilation of the superficial characteristics of dissent without the system challenging ideologies - actually serve to bolster the status quo. Part of a larger general phenomenon of co-option of dissent.
This was probably first done on a large scale in the early 70s as the images, body language, and lingo of the late 60s radical era was incorporated into advertising. A famous example is the Virginia Slims "You've come a long way, baby" campaign, which co-opted the attitudes of feminism to encourage women to define themselves through a superficial aspect of their appearance, the cigarette dangling from their mouths, and get cancer in the process.
Commodification of dissent has since become the primary marketing tool. Almost all of the currents in popular culture today, from the hip-hop ethos to latte drinking, were at first originated by fringe groups opposed to the status quo and opposed to mainstream society, and through the commodification of dissent have become ways in which the mainstream conforms and ways in which consumerism is encouraged.
The undisputed masters of commodification of dissent are MTV.