In November 2018, people took to Twitter to post pictures of a bizarre message regarding a YouTube popularity contest. As it turned out, thousands of internet-connected printers across multiple countries had been hacked -- each delivering the same unsolicited printout urging people to subscribe and spread the word about the YouTube competition.

The hacker who claimed responsibility for the stunt said he was trying to teach people a lesson about printer security.

The incident showed just how easy it can be to penetrate a modern printer. Luckily, the hacker didn’t have anything in mind more malicious than simply trying to increase a YouTube personality’s subscription numbers.