Graffiti is highly controversial. Some graffiti is considered great art, while still being a form of vandalism, which, of course, is illegal. However, despite its potentially destructive nature, graffiti is also a great way to understand the mood and history of a particular population within a city. It is a crucial form of direct and highly visible expression. Stickr is a system for creating non-destructive graffiti and street art. It is a series of repositionable vinyl decals that can be stuck and re-stuck, written on, and combined to make comments, call out authority, criticize, question, explore, share, show off and point out fun and amazing stuff. Unlike sticker bombing, slap tagging, spray or scratch graffiti, Stickr is temporary and removable. Inspired by the way people engage with information and each other online, Stickr provides a real life way for pedestrians to express approval, amusement, and register complaints about the city streets.