gzipped_tar writes: Fans at a recent right-wing extremist rock festival in Germany thought they were getting free T-shirts that reflected their nationalistic worldview. But after the garment's first wash they discovered otherwise. The original image rinsed away to reveal a hidden message from an activist group. It reads: "If your T-shirt can do it, so can you. We'll help to free you from right-wing extremism." Link to Original Source
You can do this in a number of ways. IBM chose to do all of them.
Why do you find that funny?
-- D. Taylor, Computer Science 350