The Creatives at Ogilvy over in the US had a pretty interesting idea for an ad for the convenience store chain called "am pm". They filled up the sides of bus shelter with real snacks, with the idea of slowly taking the snacks away over a four-week period, to reveal the tagline, “Too much good stuff.”
In two days, hungry passers-by had already shortened the campaign by breaking open the plastic casing and removing all of the snacks.. apart from the Doritos.