Do not use your "Facebook password" on Habbo. Do not use "Habbo123." Use a password manager (Bitwarden, 1Password) to generate a 20-character random string for your Habbo account. A checker cannot guess random entropy.
However, the context matters significantly. There are two distinct types of checkers: habbo checker
The attacker logs in—not to chat or socialize, but to audit the inventory. They look for: Do not use your "Facebook password" on Habbo
To the uninitiated, the term implies a benign utility—perhaps a tool to check server status or verify a username. In reality, a Habbo Checker is a piece of software designed for credential stuffing and account validation. It is the digital lockpick of the Habbo black market. habbo checker