I just encounter a minor act of marketing genius. I was walking back to my apartment when I saw a guy inching up to a stoplight with a large (venti?) Starbucks cup on his driver’s side roof. In my Good Samaritan act of the day, I stopped at his window to let him know he had a cup on his roof. He rolled down his window and explained that it was a promotion and the cup was stuck up there with a magnet. Feeling kinda dumb, I walked away when the people from the car behind rolled down their window and asked me, “What’s going on? Does he want that cup on his roof?” So the buzz is already beginning…