Culture jamming

I took a great film class at UNC and one of the subjects we looked at was culture jamming. I can't remember it specifically but it had something to do with U2. One thing i love about new york city, is the great culture jamming. People love to express themselves and aren't shy about modding existing works of art. I think of it as a beautiful conversation, in which one person takes an unfinished sentence and articulates it in a different way. Flickr has a group called Altered Pedestrian Signs. Check it
Jammed Ped Signs