Four buildings in San Francisco were used for sending post-it messages to communicate with the neighbours.
People created collages of different characters, including Hello kitty, pac-man, and sent messages like 'we r hungover' and 'hire us' as post-it messages and hung them on their windows.
Participants reportedly also made plans to meet up for drinks with this unique way of sending messages to friends and neighbours.
An #SFPostIt tumbler deemed the new form of communication "San Francisco's newest social media platform, "according to SFGate blog .
