Back when I was a fair bit younger, my father and I upgraded our old 286/486 to a snazzy Pentium and a fresh copy of the just-released Windows 95. I seem to recall a strange Easter egg on the upgrade process which I've tried searching for and am unsure whether I remember it correctly or not.
When installing the new operating system, a dialog appeared notifying the user that 'The hard disk is about to be formatted and all data will be lost', with an 'ok' and 'cancel' button as well as a countdown timer of sorts. However when you attempted to press either of these buttons, they would shift across the screen away from your cursor, while the countdown continued towards zero.
When it reached zero, with a flustered user desperately trying to press either button, a message appeared along the lines of "just kidding", and the installation process continued.
I'm not sure if this was part of the actual Windows install process, or some obscure third party thing. However I was wondering if anyone else recalls such a user experience?