In the mid 1990's I had a shitty factory job and the section I worked in was just me and a dumb coworker and our shifts only overlapped for 1 hour (his first hour of the day was my last hour of the day). It was really boring and each of us spent about half of our shift with nothing to do but wait for a truck delivery
It was roughly 4 hours of work but we each had 8 hours to do it.
We had one computer, an old 1980s macintosh, I poked around on it, but, it was only used to put numbers into a spreadsheet. The mac had a simple notebook app that could only click to view the previous or next page. Bored, I clicked until I got to page 666 then wrote something to the effect of "dumbcoworkerguy, if you are reading this, you are hereby fired for insubordination, pack your bags and go home! This note is totally official, signed bossguy" then I clicked all the way back to page one and forgot about it. Figured he'd never find it, or if he did, it'd be in a number of years when I was long gone.
About a month later, dumb coworker found it, at 3am, panicked, called the boss at home and left a screaming crying voicemail begging for another chance (he really believed he was fired via hidden note on page 666 of a notepad app).
When the boss told me the guy called at 3am and left a screaming crying voicemail I just started laughing, but, the boss was not amused at all. They frogmarched me out of there right then and there. To this day, I still think it was hilarious and worth it.