Don't - one person's pranking is another person's bullying.

You just gave me an awesome prank to pull on my wife. Thanks!

We'd change their desktop background to something stupid

Put one of them fake ransom ware screens

Open fakeupdate.net put it in full screen (F11) and watch them debating how much of their work was unsawed.

In our office, any time someone leaves their screen unlocked, we turn everything upside down in the display settings. Good way to remind people to Win + L when they get up. 😆

I am not sure this works anymore or if it ever did since I heard about it years ago, but when you send an email to someone on something like gmail who doesn't use some form of adblocker, be sure to put some hidden text in whatever color the background of their client is. Apparently they'll eventually start seeing ads for that specific thing you hid in the email since those emails are most certainly scanned so you can get targeted ads (especially gmail and most likely outlook as well).

Hit my boss with tellyourpartner.org earlier this week, a website that anonymously texts your partner with a list of STIs you select and a suggestion to get tested. Be careful tho it kinda back fired and he messaged a few of his exes lmao