If you saw the letters CID or DOC on your kid's phone, would you know what they mean?

Several months ago, 5 on Your Side revealed codes that teens use to hide information from parents, and now we've discovered even more.

Cyber experts say it's nearly impossible to keep up with teens and their tech.

"The second you think that you think you have it under control and you know everything they're doing, we don't. They are very savvy," said Tina Meier, who founded the Megan Meier Foundation to teach families about internet safety.

Meier says if you see some of the codes on your children's phones, don't panic. Instead, talk with your children about what may be troubling them and create an open dialogue.

She also suggests not just keeping an eye on their screens, but keeping an eye on their behaviors. If their grades start dropping, that's a red flag.

If you'd like to test your texting knowledge, see if you can decipher any of the codes below.