For example, CD9, P911, MOS, and POS all mean “parents are nearby.” They’re used to quickly change the topic or switch to a different app.

As young marines, Peter MacDonald and Thomas Begay transmitted top secret military messages using their native language. It was an undercover mission that changed U.S. intelligence operations forever.

Apple has added a 'secret code' to iMessages, letting users check if their private conversations are being spied on.