The occasional hack for work, breaking into machines we need to fix because waiting on the IT departments of various customers can take a while. Usually with a customers consent (Just a non-IT person).
Then there was college, They added custom signatures to the AV scanner to detect games, which was a shame, as they were good computers for their time, and were in a nice isolated location for gaming..
It was an old DOS based AV scanner, and I managed to get around it by renaming the config file, and dropping in one I tweaked myself, to have a blank password.. Then I could use this blank password to terminate the TSR, remove the game sigs, etc.... Once the TSR was gone, we would load on our games, and then use Norton Disk Doctor, to flag the folder as a "Volume Label".. which hid it just fine.. Next time, we'd just unload the AV scanner, remove the Volume Label flag, and game on!