Stalking people as they check-in on Foursquare to cafe's reminded me of this "Foursquare stalking prank" video. Scaling this campaign is the problem but if done during an event like a Comic Con, Olympic Games or similar you could get critical mass.
This is the same agency behind the Kotex: Pinterest campaign and the way they have justified the stunt with the number of engagements and impressions is similar.
