HP LaserJet 4s squarely date TFA’s prank in the early-mid 90s. I can agree with you that lame corporate April Fool’s Day jokes on the Internet are overdone; but 1990s-era campus sysadmin’ing ruled. Sysadmins kept a close eye on things to ensure no one (especially the servers) got hurt, but computer geeks were far from mainstream and a spirit of playful tolerance and taking-care-of-our-own prevailed. Well do I remember telneting to sendmail on port 25 and sending spoofed email to classmates…
The university-wide email was probably too much but displaying INSERT 5 CENTS on an HP LaserJet 4 for a day is great.