A couple of years ago, I set autocorrect in Word to replace a coworkers name with “Matt The Dork Brown.
Took him several months and god knows how many sent docs to figure it out. :-)
It wasn’t April Fools Day, but I once set a coworker’s screen saver to the blue screen of death and a 10 second countdown to complete system failure, including a warning that all data stored on the computer would be lost. She fell for it completely. You should have heard the shrieking when it activated. Very gratifying.
I did that to my supervisor at B of A in the late 90s. Only I just replaced his name with “Bozo”. He responded by filling my overhead credenza with popcorn.
Which I responded to by emptying his desk on a Sunday, lining his drawers with painters cellophane and turning all four of them into an aquarium.
His response was to have the regional head counsel call me into a meeting with the VP of our department to accuse me of swearing at a vendor....which I had, so I couldn’t deny it - in jest (she and I would later date for a couple years) After 5 minutes of me sweating, they couldn’t keep from laughing.
We kind of toned down after that: we both knew one of us was going to get killed.