Reminds me of the day,
one April 1st in the mid-90s, when a wandering sheep mysteriously appeared on the desktop of every machine on my school network as part of the login script. It's amazing how easy it was to mock up a convincing Novell login screen in Visual Basic in those days. One could (hypothetically, of course) set it running on a machine known to be frequented by admins, and it would feign a BSOD and force a (normal) reboot once it had harvested the credentials. It was a simpler time.