A woman went viral online after figuring out what the code '23-19' used in the movie Monsters, Inc. actually means - and people can't believe they didn't know about it sooner

Next time you watch Monsters, Inc (which we definitely recommend you do soon) keep an eye out for this subtle reference.

No matter your age, the reality is you're never too old to sit on the sofa and watch Mike Wazowski and Sulley befriend the adorable Boo. But, there are many details of the childhood classic that you may have missed when you were younger, including the secret message behind '23-19'.