You know when a girl accuses a guy of looking at other women? Well, just watching doesn't hurt, does it? Well, it might cost him a slap or a bond, but it certainly doesn't hurt his vision. But there are things that can seriously harm you just by looking at them long enough. Okay, let's leave the sun and the flash for welding. These are the images behind the phenomenon called the McCollough effect, which can distort your vision. Distortion of vision can last for an hour or as long as three months! And as Tom Scott says, telling someone on the internet not to do that is like telling a five-year-old not to stuff beans up their nose. So, don't try the McCollough effect!
