The fictional "Stop Childhood Obesity" campaign, one of the mildest examples I could find - by Creative Vein

Ad people are a creative lot, but they've got to constraint themselves lest they offend their clients.

Well, not at the Chip Shop Awards: the annual advertising award lets the creative types run wild. Here's what they came up with, if they weren't afraid of being fired by their clients: Link [warning, totally tasteless and offensive ads therein] - via Adweek