Just read this fun story:  "An anonymous person emailed in to say that they'd launched a campaign just last night where they're hiding cash all over San Francisco, including outside our office. 'This will continue indefinitely. There is nothing commercial behind this. It is a social experiment,' they wrote. 'Our Twitter page will show people where the money is hidden. There are a few hundred dollars hidden last night already, and this will continue. We have two $100 bills hidden and some $20s.'"  Turned out to be true.