The Sims 4 developer Maxis has put a special "feature" into the game for those who decide to pirate it, according to this Player Attack report (as reported on by Blue's News). Maxis decided to avoid using a DRM scheme for the game, instead opting to utilize the pixels that are normally used to censor nudity in a very creative way.
When a Sim in the pirated version of the game changes clothes or uses the bathroom, their nudity is covered up with pixels, but when they complete such a task, that censored pixel cloud remains on the character. Eventually that tiny pixel cloud covers the entire screen making the game pretty much unplayable.
But the most interesting part of the story is that those who pirated the game didn't realize this quirk wasn't a bug; they took to the official The Sims 4 forums to ask about the bug - in turn outing themselves as pirates.
Source: Blue's News