My own ISP...
Not naming any names but my ISP just needed to update some settings to solve a query I had open with them, and they asked me to make a new admin account on my router with ... slightly more obscure credentials than admin:admin, but not much. It was blatantly obvious that this was the standard username and password combo they used for all such enquiries.
I replied that I wouldn't use those credentials, but offered them an alternative with the username 'securitymatters' and a proper password. They accepted it.
Biting the hand that feeds IT
