Played a small part in my high school racking up a 5 figure internet bill, having been previously employed for the school to fix small issues after class two days per week I knew how poor the security was. They canned the teacher and his army of student helpers, and a few of us got jaded and decided to use it to our advantage. Started off with just me and a few friends using a workaround to get free printing and internet, then a few started doing the same to get utorrent working without using our student allocated data. From there one friend began bringing his laptop in to download all day onto an external drive, to him selling discs of pirated media which was downloaded on the school internet connection to other students.
This in itself was a bit of an issue when he was downloading several gigabyte worth of data per day when students got allocated like 200mb per year... Thinking fuck this is going to be too easy to track back to a small group of us, we spread around how to do it to less tech savvy students in other years who didn't know our names to disseminate it further, knowing they would tell other less IT savvy students how to do it (it was insanely simple). Knew this would spread it further and further through the whole school, removing it further from myself and the rest of us who worked out how to streamline it. Kind of realised how deep it got when in a single classroom of 20 PC's, nobody was using their student internet and at least 5 were torrenting games / movies... Also realised a few of my friends had put keylogging software on most PC's to try and mess around with peoples accounts, so I made a simple batch file I saved to my student drive to remove it as soon as I got on the PC.
Now when the term ended and the school had a massive, unaccounted for internet bill shit started to hit the fan, they tried closing the loophole, but just created a game of whack a mole until they just flat out banned students opening executable files not on the resource drive. Now they suspected which students started it, but couldn't prove it, I never torrented personally, nor kept any files associated with it on my student drive. Couldn't say the same for my friends, but all I had was that one fucking batch file...
Few of my friends got busted and hit hard, 1 got his account banned for a year, another for a semester, 1 nearly had the cops called on him as the idiot had keylogging transcripts on his student drive and a bunch of teachers passwords. Me, all I had was that one batch file, nothing else, thing is nobody left employed within the school knew what it was or what it did (they axed IT for a few years at my school). Eventually after threats of suspension for having "hacking software" I demanded to see the new, externally employed admin. Told him to inspect the simple coding and tell me what it did and pointed out I was just doing his job for him. Got out of it all with a warning, still never paid for internet or printing in all 6 years of high school...