My tinfoil hat is getting pretty beat up

WaPo:

It sounds like a conspiracy theory, but it isn't. The pages coming out of your color printer may contain hidden information that could be used to track you down if you ever cross the U.S. government. .....

With the Xerox printers, the information appears as a pattern of yellow dots, each only a millimeter wide and visible only with a magnifying glass and a blue light.

By the way, if you're looking for causes, the EFF is the technology specific equivalent of the ACLU.