I remember a teacher used the password "music". We had every user's password in plaintext. This was useful when installing a new Windows domain controller and setting all the passwords (about 30 employees in the school) instead or copying hashes or letting them set their own passwords. In hindsight, I find it batshit crazy that some stupid intern (me) walked around the school with a sheet of paper with literally everyone's password on it, logging into people's systems where necessary or potentially forgetting the sheet somewhere. I'm not saying this never happens anywhere in the world anymore, but I do think security mindset changed in the last decades.
Teacher had password written on the BACK of the clipboard they carried around everywhere.
Said teacher's password was 'qwerty'.
(Yes, it worked)