You can copy but you can’t hide

A secret code embedded in many color laser jet printers allows the US government and any other organization capable of reading the cipher to identify when the copies were made and on which particular machine, according to research conducted by the Electronic Frontier Foundation (EFF).
Among the copiers found to include the secret yellow dots are ones made by Brother, Canon, Dell, Epson, HP, Konica/Minolta, Kyocera, Lexmark, Ricoh, Tektronix/Toshiba and Xerox. The dots are yellow, less than one millimeter in diameter, and are typically repeated over each page of a document. The pattern can be seen using a blue light, a magnifying glass, or a microscope.
Do you think they hide something in our coffee too?