When I was a university student, we had access to network printers, for a fee, but only from the schools computer. As I broke ass student, I wasn't about to pay .10$ a sheet. I started messing around a lab computer and had the idea to try and connect directly with the printer on the network instead of going through the system portal.

I found the printer's IP address, then plugged my laptop in a random internet plug on the wall (don't laugh at my lack of technical terms), and added the printer manually. I get the security prompt and tried admin/admin... and it fucking worked, not only with that lab's printer, but with all of them.

I found one of the nicer printer for the university office workers, one that could do everything (recto/verso, colours, holes, stapling, etc.). I renamed my laptop in a name similar to all the university computer names, just in case.

Torrented PDF of the expensive textbook ? Printed, in colour, on both side of the page. When people asked, I told them someone I know with a nice printer did it for me. I told no one my secret, but provided some to my close friends, telling them I had asked that someone I know to print another copy. I was afraid of getting caught and forced to pay for every page I had printed.

Funnily it worked the 4 years I was a student. No one ever realized I was printing thousand of pages in colours each semester. I guess since I was directly connected to the machine, and not using the portal, it never showed up on whatever management system the university used for their printers.