The Game Boy Camera was a weird accessory to begin with: It allowed you to take small, grainy photos with your Game Boy, which could then be printed out into small, grainy stickers if you hooked it up to the Game Boy Printer.
But what made it downright bizarre was the creepy messages hidden through it. The system came loaded with several mini-games and image editing features, among which was a "Run" option. Every kid who ever owned a Game Boy Camera was terrified to accidentally select Run from the menu, because if they did, the system would freeze for a moment and show one of three vandalized faces...
... accompanied by the phrase "WHO ARE YOU RUNNING FROM?" and this sound.
Even if you managed to steer clear of the Run option, though, you were still under permanent risk of being randomly subjected to inexplicable images like that if you happened to come across a system error (like if the game couldn't find the printer or something). So, while playing with the Game Boy Camera you always had to be extra careful if you didn't wanna run into something like this:
Here's the third error face, and there were two more that were only present in the Japanese version, which is kind of puzzling, because it means that someone at Nintendo actually sat there and said "No, no, the American market will never go for these faces, let's get different ones."
There's more: If you looked at the Game Boy Camera's credits sequence and pressed "B," the screen would be overtaken by a self-replicating dancing Japanese person (possibly Mario's creator, Shigeru Miyamoto):
The Game Boy Camera wasn't a big hit (I cannot imagine why) and was eventually discontinued, but its legacy of terror lives on in the nightmares of thousands of gamers and lo-res photography enthusiasts.