RM LAN Manager (warning: nerd comprehension skills required)
For the computer geeks among us... does anyone remember this? Maybe not quite the naughtiest thing ever, unless you were being judged under the withering glare of an IT teacher, but favourites at our school included:

1) Bypassing the decidedly shonky quota management system. This little backdoor went unnoticed for quite some time, with several of us using it to escape the irritation of having to decide which coursework you'd delete so the bastard system would let you log in. (The school did a nice line in selling emergency floppy disks.) Or at least, it did up until I copied an entire CD-ROM to my user area and the school server ran out of disk space.

2) Crashing the Windows 95 RMLM client on logout, leaving the computer locked with no usable desktop and no login screen. This was merely an amusing trick to get the teacher running around the IT room resetting machines until one day I found two related facts; if you found some way to set a desktop wallpaper while you were logged in, it would remain after the LAN Manager crashed. And if you pressed PrtScr before logging in, you could set the login screen as your desktop wallpaper. NEXT LEVEL.

Challenge One was to see how long someone would try to log in to the frozen PC for, and once they gave up, how long a stumped teacher would scratch their head at it.

Challenge Two was seeing how much you could deface the login screen before anybody noticed something was up. Turning the RM logo upside-down, removing the password textbox... my biggest success at this ("success" being defined as someone sitting down without immediately going, "sir, someone's ruined the computer") was loading the login screen in to Paint Shop Pro and tilting everything by an angle of 15 degrees. Someone tried logging in to that for a good five minutes.

3) The way our version of RMLM stopped you accessing any settings you shouldn't was to run a background task that closed any window which said "System", "Properties" or "Control Panel" in the title bar. Yes, I'm serious. Good luck changing the properties of your Word document. Turned out that by repeatedly opening and closing property dialogs at speed you could get it to kill random user processes, including, if you were lucky, itself.

We were surprisingly responsible with this sense of unbridled power, as it happened, maybe because most of us were under some threat or other of suspension of network access by this point, although after we showed it to some kid in the year below us he used the new knowledge to open up a command prompt and delete most of the files on the C:\ drive (for some reason RMLM required a local install of Win 95, where I'm sure the older versions booted from network from Netware - memories may be hazy) which made the network administrator various kinds of not happy.

I wouldn't say I gained a reputation, but when a blown fuse took out a room of 486/25s and they wouldn't turn back on, the teacher spent quarter of an hour interrogating me before finally admitting I had nothing to do with it and sending for the caretaker.
(Timberwolf, Tue 13 Sep 2011, 21:27, 2 replies)

quota.ini for you too?
( Ungersven would support SpankyHanky's patreon, Wed 14 Sep 2011, 15:57, closed)

We never seemed to be able to get quota.ini changes to stick. Ours was abuse of the long file name support. You got a file share on the server supporting the Windows 95 PCs, and a file share on the server (Netware, IIRC?) supporting the Windows 3.1 ones.

Quota for the 95 share was checked when logging on to a 95 box, quota for the 3.1 share checked when logging on to a 3.1 box. However, if you saved a LFN file on the 3.1 share from one of the Win95 PCs, it was somehow to all intents and purposes invisible to the Windows 3.1 computer - and thus not counted by the (client-side!) quota manager.
(Timberwolf, Wed 14 Sep 2011, 20:09, closed)