![Everything You Ever Printed Had a Secret Code On It](https://hight3ch.com/wp-content/uploads/2015/12/everything-you-ever-printed-had.jpg)
This is why you can’t print black and white when low on yellow ink. Each laser printer ever produced embeds a secret code on each printed page. It does that so the government can trace back the printer if they find someone printing counterfeit money with it.