It takes hundreds — sometimes thousands — of people to create a film or TV series, so it makes sense that over time these technicians will incorporate some hidden messages into their work. Case in point is the mysterious code “A113” which appears in so much of our entertainment — especially animation. The team at Vulture wanted to learn why, and they found the answer in the video below. Another code which appears in our daily lives is “YKK” on our zippers. So why exactly do these 3 letters show up on 99% of our pants and shorts? Click play on BrainStuff‘s explainimator below to find out. And as an extra bonus, I’ve also attached a Business Insider video explaining why all of our jeans come with that strangely useless little square pocket we never seem to use.