Since basically the dawn of video games, "rumors" about games have been "leaked" on school playgrounds and internet forums with the "infallible" "source" of "My Uncle Works At Nintendo."
As the numerous scare quotes might indicate, these rumors were always a load of baloney, which has made the mystical "Relative who works at [game company]" a meme for decades since. However, Did You Know Gaming has uncovered a real leak that came from a real kid whose real dad worked at Nintendo: the Super Smash Brothers 3DS roster leak of 2014.
The kid was the son of a Nintendo of America employee whose job it was to send the game to the game's rating board, the ESRB. The son of that employee was able to grab footage of the game and share it with their friends, one of whom posted it on 4chan, ensuring a widespread leak. The leak revealed some unannounced fighters at that point like Shulk and Dark Pit.
While the leak is itself ancient history at this point, social media users, particularly fans of Nintendo and Super Smash Brothers, was thrilled that a real "Dad Works at Nintendo" leak had happened in real life.
Unsurprisingly, the story doesn't have a happy ending, as the dad was fired from Nintendo after the leak.