The joke was that if you typed your password into chat, then chat would add ***** for everyone else but still show you your own password.

So for instance if I type my password out ******** it will show as just *s to you because it's auto censored by the system since it's my password. But it wont censor it for me since it knows that I already know my own password. You can test it by typing out your password. You'll see your own password but everyone else will just see *'s