"A major fast-food chain ran a campaign promoting the McRib sandwich by mapping roughly 300 billboards in a region and triggering stop-screen ads that showed a photo of the McRib and offered drivers the option to reroute to a nearby location; about 8,400 drivers chose to reroute immediately and the ads made roughly 6 million impressions. The campaign did not track later visits (though the navigation app used is capable of very granular GPS tracking), and the coordination of out-of-home billboards with in-car ads drew criticism as invasive or "creepy." - Monica Burton