Johnny Monsarrat Leaves a Few Messages
Summer 1996. This one wasn't my idea, but I helped. At Turbine, my videogames company, Dan goes on a business trip, and while he's away, somebody gets the idea to cover his office with pink message slips. Tim hands out a bunch to everyone, and we each fill out 10-30 of them. This isn't nearly enough, so we use a bunch of blank ones too.
We took 6-foot-long strips of tape and attached the memos to them, and then hung the long strips on the wall. This was more protective of the paint on the wall.
When Dan returned from his trip, we told him he'd gotten a few phone messages. Joe cleverly hid a camera in the office so we got his reaction on video. The messages stayed in the office for weeks.