For as long as video games have existed, so too have pirates. No matter the personal reasoning behind their choices, there's always gamers out there eagerly waiting for the second a game launches, not to buy it, but rather so that the scene teams can get their hands on it and undo the DRM protecting the game's files, or so that it can be played on an emulator.
Sometimes, these quick DRM-removal uploads miss something, and the game KNOWS that you're playing an illegal copy. Depending on what tricks the developers left in the game, it could mean a secret hidden message that calls you out on your actions, or it's a simple way of messing with the player. One of the most notable "anti-piracy" messages comes from Pokemon Fire Red and Leaf Green, which famously has a message that triggers when playing a copy on an early version of a GBA emulator, or so the story goes. While talking to the ferryman who checks your ticket to board the S.S. Anne, he'll let you through, but not before giving you a passing message of, "By the way: if you like this game, buy it or die".
The legitimacy of the text has been debated for years, and interested dataminers have tried their best to find this mysterious message in the ROM's files. Present in only a single incredibly early ROM dump and nowhere else, the most sensible explanation is that the original hacker who backed up their game left the text in a place where it wouldn't immediately be found, but would be seen by just enough people to make waves across the internet.
And it did, for years. Both startling and funny, the message's legendary status likely inspired developers to include such references in their data. A legitimate occurrence of a game's developers having their last laugh at pirates can be found in Game Dev Tycoon, a game about making games. As you build upon your career as a video game maker, your company will grow and prosper...at least until you're given a report within the first hour of the game. If you're playing a "cracked" copy--which was uploaded specifically by creators themselves, they left a sneaky surprise. Your studio has tons of fans, and your games are well-liked, but it seems that...gamers keep pirating your games! Game Dev Tycoon goes meta, claiming that if the players don't support the official release and rely on piracy, then the company you've spent a while managing will go bankrupt! Well played.
Recently, fake anti-piracy messages have been flooding YouTube, attempting to make realistic-looking or creepy-pasta level AP text, proving that players are still amused by hidden messages from developers still to this day. Whether it's Pokemon Black and White trolling the player by not giving you any EXP at all, Earthbound upping the encounter rate to an unbearable degree to punish you, or Mirror's Edge taking away the ability to run, what's your favorite anti-piracy message or effect?