My HS put networked computers in every classroom a couple years before I graduated (so '95 or '96). They put predictable passwords on all the teacher accounts, and all teacher accounts had write access to network shares. Those of us who figured that out stashed copies of the Doom WAD file (the one file too big to fit on a single 3.5" floppy) all over the network under different names. So even after they figured out we were in and started forcing teachers to change their password, there were still a dozen or more copies spread over the network.

Student access was enough to copy the WAD file locally over the 100mbit ethernet if you knew where to look. And we all carried the rest of the game around on floppy. So any time we got access to the computers we were playing doom. We also passed around floppies with different mod files. The chicken launcher was everyone's favorite.