Love how simple but effective this idea is. To remind employees that "Bring your kids to work day" was coming up, BBDO, an ad agency in New York, cut pieces of acetate, scribbled on them with crayon and then quietly stuck them on 500 of their employees' computers.
"Everyone in the company came into work to find their computers vandalized with crayon scribbles. To promote "Bring your kids to work day," childlike art was hand-drawn on acetate sheets, which were trimmed to fit the screens. Building security secretly unlocked over 500 offices the night before so the acetate sheets could be affixed to everyone's computer monitor."
Sure this may have given some people a heart attack but isn't that part of the fun?
Found via Why Me Design