There are no hidden "secret codes" in AdventureQuest (AQ) that grant exclusive items or stats. Artix Entertainment (AE) is transparent about game mechanics.
Any site/video/person claiming "secret codes for 1M Z-Tokens," "unlock all classes," or "admin commands" is phishing for your account credentials. AE staff will never ask for your password.
Bottom Line: Play fair. The wiki (AQ Encyclopedia) documents every item/quest legitimately.