If you’ve been to a big US city, chances are that you’ve experienced video-projected ads in the subway. They are annoying as hell, but fear not, because a group of people in Berlin found a quite ingenious way to completely disrupt the video without breaking anything except the ad itself.
They use mirrors (to distort the images and break it into little shards), magnets (to attach the distorting device to the projectors) and a lot of ducktape (to create the casing for the device). [Thanks Karl!]